Long-term effects of very low-carbohydrate and high-carbohydrate weight-loss diets on psychological health in obese adults with type 2 diabetes: randomized controlled trial

Effect of Low-Fat Diet on Depression Score in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials

CONTEXT

Current evidence on the effect of a low-fat (LF) diet on depression scores has been inconsistent.

OBJECTIVE

To explore the effect of an LF diet on depression scores of adults by systematic review and meta-analysis of randomized controlled trials (RCTs).

DATA SOURCES

The PubMed, ISI Web of Science, Scopus, and CENTRAL databases were searched from inception to June 7, 2023, to identify trials investigating the effect of an LF diet (fat intake ≤30% of energy intake) on the depression score.

DATA EXTRACTION

Random-effects meta-analyses were used to estimate pooled summary effects of an LF diet on the depression score (as Hedges g).

DATA ANALYSIS

Finding from 10 trials with 50 846 participants indicated no significant change in depression score following LF diets in comparison with usual diet (Hedges g = -0.11; 95% CI, -0.25 to 0.03; P = 0.12; I2 = 70.7% [for I2, 95% CI, 44%, 85%]). However, a significant improvement was observed in both usual diet and LF diets when the content of protein was 15-20% of calorie intake (LF, normal protein diet: n = 5, Hedges g = -0.21, 95% CI, -0.24 to -0.01, P = 0.04, I2 = 0%; usual, normal protein diet: n = 3, Hedges g = -0.28, 95% CI, -0.51 to -0.05, P = 0.01, I2 = 0%). Sensitivity analysis also found the depression score improved following LF diet intervention in participants without baseline depression.

CONCLUSION

This study revealed that LF diet may have small beneficial effect on depression score in the studies enrolled mentally healthy participants. Moreover, achieving to adequate dietary protein is likely to be a better intervention than manipulating dietary fat to improve depression scores. However, it is not clear whether this effect will last in the long term. Conducting more studies may change the results due to the low-certainty of evidence.

SYSTEMATIC REVIEW REGISTRATION

CRD42023420978 (https://www.crd.york.ac.uk/PROSPERO).

The effect of a low-calorie diet on depressive symptoms in individuals with overweight or obesity: a systematic review and meta-analysis of interventional studies

BACKGROUND

Individuals with overweight or obesity are at a high risk for so-called 'atypical' or immunometabolic depression, with associated neurovegetative symptoms including overeating, fatigue, weight gain, and a poor metabolic profile evidenced e.g. by dyslipidemia or hyperglycemia. Research has generated preliminary evidence for a low-calorie diet (LCD) in reducing depressive symptoms. The aim of the current systematic review and meta-analysis is to examine this evidence to determine whether a LCD reduces depressive symptoms in people with overweight or obesity.

METHODS

Eligible studies were identified through PubMed, ISI Web of Science, and PsycINFO until August 2023. Standardized mean differences (SMDs) were derived using random-effects meta-analyses for (1) pre-post LCD comparisons of depression outcomes, and (2) LCD v. no-diet-control group comparisons of depression outcomes.

RESULTS

A total of 25 studies were included in the pre-post meta-analysis, finding that depression scores were significantly lower following a LCD (SMD = -0.47), which was not significantly moderated by the addition of exercise or behavioral therapy as a non-diet adjunct. Meta-regressions indicated that a higher baseline BMI and greater weight reduction were associated with a greater reduction in depression scores. The intervention-control meta-analysis (n = 4) found that overweight or obese participants adhering to a LCD showed a nominally lower depression score compared with those given no intervention (SMD = -0.29).

CONCLUSIONS

There is evidence that LCDs may reduce depressive symptoms in people with overweight or obesity in the short term. Future well-controlled intervention studies, including a non-active control group, and longer-term follow-ups, are warranted in order to make more definitive conclusions.

An Overview of the Potential Role of Nutrition in Mental Disorders in the Light of Advances in Nutripsychiatry

PURPOSE OF REVIEW

As research on the potential impact of nutrition on mental disorders, a significant component of global disability continues to grow the concepts of "nutritional psychiatry, psycho-dietetics/nutripsychiatry" have taken their place in the literature. This review is a comprehensive examination of the literature on the the potential mechanisms between common mental disorders and nutrition and evaluates the effectiveness of dietary interventions.

RECENT FINDINGS

Inflammation, oxidative stress, intestinal microbiota, mitochondrial dysfunction, and neural plasticity are shown as potential mechanisms in the relationship between mental disorders and nutrition. As a matter of fact, neurotrophic factors, which make important contributions to repair mechanisms throughout life, and neuronal plasticity, which plays a role in mental disorders, are affected by nutritional factors. In metabolism, the antioxidant defense system works with nutritional cofactors and phytochemicals. A balanced, planned diet that provides these components is more likely to provide nutrients that increase resilience against the pathogenesis of mental disorders. Nutrition can be considered a risk factor for mental disorders. Therefore, developing public health strategies focused on improving diet may help reduce the global burden of mental disorders and other related diseases.

Influence of Metabolic Dysregulation in the Management of Depressive Disorder-Narrative Review

Depressive disorders are heterogeneous in nature, and their global reach makes them the cause of suffering for a million individuals worldwide. Standard treatment does not work for one in three people, and side effects can significantly reduce the quality of life. A multidisciplinary approach allows for a broader insight into the nature of the disease, given its complex etiology. One of its elements is the hypothesis of inflammation, which also accompanies obesity-related disease. Obesity and depression interact, causing many researchers to develop new non-pharmacological treatment methods for both diseases. One suggestion is physical exercises that have great potential to be used in clinical practice. They can exert changes on the central nervous system and thus modulate mood. Another is diet, which concentrates on active molecules that also affect the central nervous system (CNS). There is an urgent need to create appropriate criteria and recommendations that systematize existing knowledge and allow it to be used in practice. There is an urgent need to create appropriate criteria and recommendations that systematize existing knowledge and allow it to be used in practice.

The effects of carbohydrate-restricted diet on psychological outcomes: a systematic review of randomized controlled trials

CONTEXT

Carbohydrate-restricted diets are widely used as an effective treatment tool for many chronic diseases. The impact of these diets on physical health is well known, but their impact on psychological health is less well described in the scientific literature. This is an important aspect to focus on, especially if the diets are to be sustainable in the long term.

OBJECTIVE

The objective of this study was to systematically review the scientific literature describing the effect of carbohydrate-restricted diets and ketogenic diets on psychological outcomes, as observed in randomized controlled trials. Additionally, the potential synergistic effect of carbohydrate-restricted diets and exercise or social factors on these outcomes was researched.

DATA SOURCES

Five databases (Web of Science, PubMed, Scopus, ScienceDirect, and MEDLINE Complete) were searched without restriction of publication date.

DATA EXTRACTION

The first data extraction was made in October 2020 and the second in May 2022. Abstract screening was performed by 3 independent reviewers. The quality of studies was assessed using the Jadad scale.

DATA ANALYSIS

Sixteen randomized controlled studies were included in the analysis. Five studies focused on clinical populations, 9 on obese/overweight populations, and 2 on healthy populations; all studies examined adult people. Four psychological outcomes were identified (quality of life, mental health, mood, and fatigue), and they were examined in connection with a very low-carbohydrate or ketogenic diet.

CONCLUSION

Daily low-carbohydrate intake may not negatively affect psychological well-being, and low-carbohydrate diets and ketogenic diets are no worse than other diets in this respect. An intervention of 12 weeks or longer can bring benefits in psychological well-being. The synergistic effect of diet and exercise or social factors was not reviewed due to lack of evidence.

Dietary eating patterns, dairy consumption, and anxiety: A systematic literature review

BACKGROUND

Nutrition affects both physical and mental health but evidence is mixed regarding potential associations between anxiety and diet, particularly dairy consumption. We conducted a systematic literature review (SLR) of dairy consumption and/or various dietary patterns and risk of anxiety.

METHODS

Literature searches were conducted in PubMed and Embase. All study designs except case reports, small case series, and SLRs were considered for inclusion. Reference lists of previously published SLRs were reviewed for any relevant additional studies. Studies of populations without dairy sensitivities exploring the association between dietary patterns and/or dairy consumption and anxiety published through May 2022 were identified using predefined eligibility criteria. Study quality was determined using the Academy of Nutrition and Dietetics Quality Criteria Checklist.

RESULTS

For this SLR, 132 studies were included; 80 were cross-sectional. Studies examined different dietary patterns (e.g., Mediterranean, gluten-free) and anxiety using various anxiety scales, with 19 studies specifically reporting on whole dairy consumption and anxiety. Dairy consumption was significantly associated with a lower risk of anxiety in 7 studies, while the remaining 12 studies showed no significant associations. Evidence was mixed for the association between various dietary patterns and anxiety, but more studies observed a lower risk of anxiety with greater adherence to "healthy" diets (e.g., Mediterranean, diet quality score, vegetarian/vegan) than a higher risk. Notable heterogeneity in study populations, time periods, geographical locations, dietary assessment methods, and anxiety scales was observed.

CONCLUSIONS

The results of this SLR suggest a potential link between diet including diary consumption and anxiety, but future studies, especially with longitudinal designs that measure diet and anxiety at several timepoints and comprehensively adjust for confounders, are needed to fully understand the relationship between diet and anxiety.

Low-carbohydrate and ketogenic diets: a scoping review of neurological and inflammatory outcomes in human studies and their relevance to chronic pain

Dietary restriction of carbohydrate has been demonstrated to be beneficial for nervous system dysfunction in animal models and may be beneficial for human chronic pain. The purpose of this review is to assess the impact of a low-carbohydrate/ketogenic diet on the adult nervous system function and inflammatory biomarkers to inform nutritional research for chronic pain. An electronic database search was carried out in May 2021. Publications were screened for prospective research with dietary carbohydrate intake <130 g per day and duration of ≥2 weeks. Studies were categorised into those reporting adult neurological outcomes to be extracted for analysis and those reporting other adult research outcomes. Both groups were screened again for reported inflammatory biomarkers. From 1548 studies, there were 847 studies included. Sixty-four reported neurological outcomes with 83% showing improvement. Five hundred and twenty-three studies had a different research focus (metabolic n = 394, sport/performance n = 51, cancer n = 33, general n = 30, neurological with non-neuro outcomes n = 12, or gastrointestinal n = 4). The second screen identified sixty-three studies reporting on inflammatory biomarkers, with 71% reporting a reduction in inflammation. The overall results suggest a favourable outcome on the nervous system and inflammatory biomarkers from a reduction in dietary carbohydrates. Both nervous system sensitisation and inflammation occur in chronic pain, and the results from this review indicate it may be improved by low-carbohydrate nutritional therapy. More clinical trials within this population are required to build on the few human trials that have been done.

The effects of the ketogenic diet for the management of type 2 diabetes mellitus: A systematic review and meta-analysis of recent studies

OBJECTIVE

To systematically review the effects of the ketogenic diet on glycaemic control, body weight, cardiovascular risk factors, and liver and kidney function in patients with type 2 diabetes.

METHODS

PubMed, MEDLINE, Embase, Cochrane Library and CINAHL were searched for randomised controlled trials published between 2001 and 2021 that compared the ketogenic diet to a control diet for effects on glycaemic control, body weight, cardiovascular risk factors, liver and renal function markers in adults with type 2 diabetes for >14 days. Meta-analyses using fixed or random effects models were conducted.

RESULTS

Nineteen reports from 11 randomised controlled trials were included. Compared to the control, the ketogenic diet showed no significant difference in changes in glycaemic control or body weight, but greater increases in HDL (standardised mean difference 0.19; 95%CI 0.02-0.37; I2 = 0 %; moderate-quality evidence) and greater reductions in triglycerides (standardised mean difference -0.41; 95%CI -0.64 to -0.18; I2 = 0 %; low-quality evidence).

CONCLUSIONS

The ketogenic diet may improve lipid profiles but showed no additional benefits for glycaemic control or weight loss compared to control diets in type 2 diabetes patients over two years.

The effect of lifestyle interventions on depressive symptom severity in individuals with type-2 diabetes: A meta-analysis of randomized controlled trials

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a severe metabolic condition which is commonly comorbid with depression. Lifestyle factors are involved in the pathophysiology of both conditions; however, the role of lifestyle interventions remains unclear.

OBJECTIVE

The objective of this study is to systematically review the literature on randomized controlled trials evaluating the effect of lifestyle interventions on depressive scores in patients with T2DM.

METHODS

A systematic search was conducted in computerized databases before October 2022. A random-effects model was used to investigate the effect of lifestyle interventions on depression scores and meta-regression was conducted to assess the influence of age and disease onset.

RESULTS

Six trials met the eligibility criteria for inclusion. A statistically significant reduction in depression scores was found for groups receiving lifestyle interventions compared to controls (SMD = -0.49 [95%CI -0.89 to -0.08]; p = 0.0269]). Interventions increased in efficacy with the age of the participants but no significant correlation was found with years since disease onset. Participants in a control group receiving a less intense lifestyle intervention demonstrated improved depression scores when compared to those who received standard care or no intervention at all. Trial design and outcome measurement tools were heterogeneous between studies and limited data on antidepressant use was available which may introduce bias into the results.

CONCLUSION

Lifestyle interventions were effective at improving depressive symptom severity in patients with T2DM.

Sodium-Glucose Cotransporter-2 Inhibitors in Depression

ABSTRACT

Novel treatment strategies that refract existing treatment algorithms for depressive disorders are being sought. Abnormal brain bioenergetic metabolism may represent an alternative, therapeutically targetable neurobiological basis for depression. A growing body of research points to endogenous ketones as candidate neuroprotective metabolites with the potential to enhance brain bioenergetics and improve mood. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally approved for the treatment of diabetes, induce ketogenesis and are associated with mood improvement in population-based studies. In this column, we highlight the rationale for the hypothesis that ketogenesis induced by SGLT2 inhibitors may be an effective treatment for depressive disorders.

Effect of low-carbohydrate diet on depression and anxiety: A systematic review and meta-analysis of controlled trials

BACKGROUND

Despite considerable advances in pharmacological and non-pharmacological treatments, mental health illnesses carry many economic and social burdens. Depression and anxiety are known as mental disorders which are highly prevalent worldwide. Previous studies have shown different results. This diet has attracted enormous interest.

OBJECTIVE

This is the first meta-analysis conducted to review systematically all trials to evaluating the effect of a low carbohydrate diet (LCD) on depression, and anxiety.

METHODS

PubMed, Web of Science, and Scopus have been searched until 9 September 2021. In total, 8 RCTs (n = 590) were carried out for evaluation the effects of LCDs on depression and anxiety were included. All the trials included in the analyses evaluated patients without a mood disorder. Random model effects meta-analysis was conducted. To evaluate the heterogeneity among the included studies. The egger test was used. Subgroup analyses performed based on regions, assessment methods, carbohydrate intake and duration of studies.

RESULTS

This study did not show any significant association between a low carbohydrate diet and the of anxiety (SMD = 0.19, 95 % CI -0.10, 0.47; P = 0.20) and also depression (SMD = 0.06, 95 % CI -0.11, 0.24; P = 0.49). If one of the studies is excluded, this diet significantly increases anxiety (SMD = 0.33, 95 % CI 0.12, 0.54; P ≤ 0.001). This study showed that this diet increases anxiety in studies with <26 % carbohydrate intake (SMD = 0.31; 95%CI 0.10, 0.52; P ≤ 0.001; I² = 0.00, P = 0.52), in the Australia (SMD = 0.29; 95%CI 0.08, 0.49; P = 0.01; I² = 0.00, P = 0.42), and in studies that used the Spielberger State Anxiety Inventory (SAI) to assess anxiety (SMD = 0.33; 95%CI 0.11, 0.54; P ≤ 0.001; I² = 0.00, P = 0.54).

LIMITATIONS

One of the limitations of intervention studies examining the effect of diet is that it is difficult to blind people under intervention.

CONCLUSION

The present study did not demonstrate significant association between a low carbohydrate diet and improvement of depression and anxiety. More accurate studies are needed to reach definitive conclusions.

Type 2 diabetes

Type 2 diabetes accounts for nearly 90% of the approximately 537 million cases of diabetes worldwide. The number affected is increasing rapidly with alarming trends in children and young adults (up to age 40 years). Early detection and proactive management are crucial for prevention and mitigation of microvascular and macrovascular complications and mortality burden. Access to novel therapies improves person-centred outcomes beyond glycaemic control. Precision medicine, including multiomics and pharmacogenomics, hold promise to enhance understanding of disease heterogeneity, leading to targeted therapies. Technology might improve outcomes, but its potential is yet to be realised. Despite advances, substantial barriers to changing the course of the epidemic remain. This Seminar offers a clinically focused review of the recent developments in type 2 diabetes care including controversies and future directions.

Nutritional intervention for diabetes mellitus with Alzheimer's disease

The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.

Differences in weight loss outcomes for males and females on a low-carbohydrate diet: A systematic review

It has been widely demonstrated that there are a broad range of individual responses to all weight management regimens, often masked by reports of the mean. Identifying features of responders and non-responders to weight loss regimens enables a more tailored approach to the provision of weight management advice. Low-carbohydrate diets are currently popular, and anecdote suggests that males are more successful at losing weight using this approach. This is feasible given the physiological and socio-psychological differences between the genders. We analysed the extent and variation in weight change for males and females separately through a systematic search for all low-carbohydrate diet trials published since 1985. Very few studies compared weight loss outcomes by gender and, of those that did, most lacked supporting data. The majority of studies reported no gender difference but when a gender difference was found, males were more frequently reported as losing more weight than females on a low-carbohydrate diet. The lack of gender stratification in weight loss trials is concerning, as there are a range of gender-based factors that affect weight loss outcomes. This study highlights the importance of examining weight change for males and females separately, since as failure to do so may mask any potential differences, which, if detected, could assist with better weight loss outcomes.

Effects of Metabolic Medicine and Metabolic Surgery on Patient-Reported Outcomes Among Patients with Type 2 Diabetes

The assessment and management of patient-reported outcomes (PROs) is considered secondary to that of cardiometabolic outcomes. When assessed, health-related quality of life (HRQOL), a PRO, can yield pertinent information that cannot be obtained from cardiometabolic assessments. For instance, physical and mental distress can be quantified and treated. Moreover, treatment convenience and satisfaction can be gaged. Behavioral modification, bariatric surgery, and pharmacotherapy can improve PROs. Typically, HRQOL is responsive to changes in weight. Specifically, weight loss and weight gain are associated with positive and negative changes in quality of life, respectively. In addition, patient satisfaction can be influenced by glycemic control. Therefore, hypoglycemia and hyperglycemic episodes can negatively affect patient satisfaction. When managing type 2 diabetes (T2D), it is important to consider how therapies impact PROs. Generally, changes in clinical outcomes mirror changes in PROs. To best manage T2D, integrating the assessment of PROs with clinical outcomes is needed.

Could Polyphenolic Food Intake Help in the Control of Type 2 Diabetes? A Narrative Review of the Last Evidence

Background:

Diabetes is one of the largest global public health concerns, imposing a heavy global burden on public health as well as socio-economic development, and about 90% of adults with this condition have type 2 diabetes (T2D).

Introduction:

Beyond the hereditary factor, there are several risk factors connected to the development of this syndrome; the lifestyles play, increasingly, a predominant role in the development of the metabolic complications related to T2D and a significant role in the onset of this syndrome is played from an unbalanced diet. Polyphenolic food is plant-based food including vegetables, fruits, whole grains, tea, coffee, and nuts. In recent years, there is growing evidence that plant-foods polyphenols, due to their biological properties, may be nutraceuticals and supplementary treatments for various aspects of T2D. Polyphenols may influence glycemia and T2D through hypoglycemic properties as reduction of insulin resistance, reduced fasting blood glucose, and glycosylated hemoglobin value. Based on several in vitro, animal models and some human studies, is has been detected that polyphenol-rich products modulate carbohydrate and lipid metabolism, attenuate hyperglycemia, dyslipidemia, and insulin resistance, improve adipose tissue metabolism, and alleviate oxidative stress and stress-sensitive signaling pathways and inflammatory processes.

Methods:

This manuscript summarizes human clinical trials issued within the last 5 years linking dietary polyphenols to T2D, with a focus on polyphenolic-foods typical of the Mediterranean diet.

Results:

Polyphenolic food can also prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy, and retinopathy.

Conclusion:

Further investigations as other human clinical studies are needed to obtain the best dose and duration of supplementation with polyphenolic food in T2D patients.

'I need someone to believe in me and walk the journey with me': A qualitative analysis of preferred approaches to weight management discussions in clinical care among adults with type 2 diabetes

AIMS

To explore the preferences of adults with type 2 diabetes regarding the approach to weight management discussions in clinical care.

METHODS

Online survey of Australian adults with type 2 diabetes, recruited via a national diabetes registry. Three open-ended questions explored participants' experiences and ideal approach to discussing weight management with health professionals. Data subjected to inductive thematic template analysis.

RESULTS

Participants were 254 adults, 58% aged 60+ years, 52% women and 35% insulin-treated. Five themes were developed to categorise participants' preferences for, as well as differing experiences of, weight management discussions: (1) collaborative, person-centred care: working together to make decisions and achieve outcomes, taking personal context into consideration; (2) balanced communication: open, clear messages encouraging action, empathy and kindness; (3) quality advice: knowledgeable health professionals, providing specific details or instructions; (4) weight management intervention: suitable modalities to address weight management and (5) system-wide support: referral and access to appropriate multi-disciplinary care.

CONCLUSIONS

Participants expressed preferences for discussing weight management in collaborative, person-centred consultations, with quality advice and personalised interventions across the health system, delivered with empathy. By adopting these recommendations, health professionals may build constructive partnerships with adults with type 2 diabetes and foster weight management.

Low-carbohydrate versus balanced-carbohydrate diets for reducing weight and cardiovascular risk

BACKGROUND

Debates on effective and safe diets for managing obesity in adults are ongoing. Low-carbohydrate weight-reducing diets (also known as 'low-carb diets') continue to be widely promoted, marketed and commercialised as being more effective for weight loss, and healthier, than 'balanced'-carbohydrate weight-reducing diets.

OBJECTIVES

To compare the effects of low-carbohydrate weight-reducing diets to weight-reducing diets with balanced ranges of carbohydrates, in relation to changes in weight and cardiovascular risk, in overweight and obese adults without and with type 2 diabetes mellitus (T2DM).

SEARCH METHODS

We searched MEDLINE (PubMed), Embase (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 25 June 2021, and screened reference lists of included trials and relevant systematic reviews. Language or publication restrictions were not applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults (18 years+) who were overweight or living with obesity, without or with T2DM, and without or with cardiovascular conditions or risk factors. Trials had to compare low-carbohydrate weight-reducing diets to balanced-carbohydrate (45% to 65% of total energy (TE)) weight-reducing diets, have a weight-reducing phase of 2 weeks or longer and be explicitly implemented for the primary purpose of reducing weight, with or without advice to restrict energy intake.  DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts and full-text articles to determine eligibility; and independently extracted data, assessed risk of bias using RoB 2 and assessed the certainty of the evidence using GRADE. We stratified analyses by participants without and with T2DM, and by diets with weight-reducing phases only and those with weight-reducing phases followed by weight-maintenance phases. Primary outcomes were change in body weight (kg) and the number of participants per group with weight loss of at least 5%, assessed at short- (three months to < 12 months) and long-term (≥ 12 months) follow-up.

MAIN RESULTS

We included 61 parallel-arm RCTs that randomised 6925 participants to either low-carbohydrate or balanced-carbohydrate weight-reducing diets. All trials were conducted in high-income countries except for one in China. Most participants (n = 5118 randomised) did not have T2DM. Mean baseline weight across trials was 95 kg (range 66 to 132 kg). Participants with T2DM were older (mean 57 years, range 50 to 65) than those without T2DM (mean 45 years, range 22 to 62). Most trials included men and women (42/61; 3/19 men only; 16/19 women only), and people without baseline cardiovascular conditions, risk factors or events (36/61). Mean baseline diastolic blood pressure (DBP) and low-density lipoprotein (LDL) cholesterol across trials were within normal ranges. The longest weight-reducing phase of diets was two years in participants without and with T2DM. Evidence from studies with weight-reducing phases followed by weight-maintenance phases was limited. Most trials investigated low-carbohydrate diets (> 50 g to 150 g per day or < 45% of TE; n = 42), followed by very low (≤ 50 g per day or < 10% of TE; n = 14), and then incremental increases from very low to low (n = 5). The most common diets compared were low-carbohydrate, balanced-fat (20 to 35% of TE) and high-protein (> 20% of TE) treatment diets versus control diets balanced for the three macronutrients (24/61). In most trials (45/61) the energy prescription or approach used to restrict energy intake was similar in both groups. We assessed the overall risk of bias of outcomes across trials as predominantly high, mostly from bias due to missing outcome data. Using GRADE, we assessed the certainty of evidence as moderate to very low across outcomes.  Participants without and with T2DM lost weight when following weight-reducing phases of both diets at the short (range: 12.2 to 0.33 kg) and long term (range: 13.1 to 1.7 kg).  In overweight and obese participants without T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to 8.5 months (mean difference (MD) -1.07 kg, (95% confidence interval (CI) -1.55 to -0.59, I2 = 51%, 3286 participants, 37 RCTs, moderate-certainty evidence) and over one to two years (MD -0.93 kg, 95% CI -1.81 to -0.04, I2 = 40%, 1805 participants, 14 RCTs, moderate-certainty evidence); as well as change in DBP and LDL cholesterol over one to two years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one year (risk ratio (RR) 1.11, 95% CI 0.94 to 1.31, I2 = 17%, 137 participants, 2 RCTs, very low-certainty evidence).  In overweight and obese participants with T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to six months (MD -1.26 kg, 95% CI -2.44 to -0.09, I2 = 47%, 1114 participants, 14 RCTs, moderate-certainty evidence) and over one to two years (MD -0.33 kg, 95% CI -2.13 to 1.46, I2 = 10%, 813 participants, 7 RCTs, moderate-certainty evidence); as well in change in DBP, HbA1c and LDL cholesterol over 1 to 2 years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one to two years (RR 0.90, 95% CI 0.68 to 1.20, I2 = 0%, 106 participants, 2 RCTs, very low-certainty evidence).  Evidence on participant-reported adverse effects was limited, and we could not draw any conclusions about these.  AUTHORS' CONCLUSIONS: There is probably little to no difference in weight reduction and changes in cardiovascular risk factors up to two years' follow-up, when overweight and obese participants without and with T2DM are randomised to either low-carbohydrate or balanced-carbohydrate weight-reducing diets.

Effect of Ketogenic Diet on Quality of Life in Adults with Chronic Disease: A Systematic Review of Randomized Controlled Trials

Background: Chronic diseases adversely affect quality of life (QOL). The ketogenic diet (KD) may improve the QOL. Objective: The aim of this systematic review was to summarize the available evidence of randomized controlled trials (RCTs) to establish the effect of KD on the QOL in adults with chronic diseases. Methods: Reporting followed PRISMA guidelines. We included randomized controlled trials (RCTs) conducted on adults with chronic disease including an intervention group that received KD and a control group, and where QOL was reported as outcome. We searched PubMed, APA PsycInfo, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Library, and Clinicaltrials.gov, and the references of the included articles and previous relevant reviews, without language or time restrictions. We critically appraised included studies and narratively synthesized their findings. Results: Nine RCTs were included. The risk of bias was low, except of allocation concealment and blinding. In patients with cancer: one RCT found an improvement in overall QOL, another reported improved physical component summary, and one found no superiority of KD in all QOL domains. In patients with neurological disorders: improved QOL was reported in Alzheimer’s disease patients, whereas no difference in mental and physical health QOL was noted in patients with multiple sclerosis. In patients with obesity and type II diabetes: one RCT reported superiority of energy-restricted KD in improving role functioning, mental health, health perceptions, and pain compared with guideline-based diet, whereas in another RCT, high and low carbohydrate diets achieved comparable improvements. Among patients with knee osteoarthritis, no differences between KD and low-fat groups were noted. Dietary compliance with the KD, reported in three studies, was shown to be high. Side effects were mostly noted during the first weeks of intervention, and adverse events were not markedly different with KD and the comparison diet. Conclusions: The evidence from RCTs investigating the effect of KD on QOL in adults with chronic disease is inconclusive. The promising effect noted in some included studies and the low rates of adverse events and side effects encourage future investigations in this regard.

Effects of very low-carbohydrate vs. high-carbohydrate weight loss diets on psychological health in adults with obesity and type 2 diabetes: a 2-year randomized controlled trial

AIMS

Very low-carbohydrate (LC) diets are popular for type 2 diabetes (T2DM) management; however, long-term effects on psychological health remain largely unknown. This study reports the effects of a LC diet on mood and cognitive function after 2 years and explores the potential predictors of changes in psychological health.

METHODS

115 adults (57% males; age: 58.5 ± 7.1 years) with obesity and T2DM were randomized to consume an energy reduced (~ 500 to 1000 kcal/day deficit), LC diet [14% energy as carbohydrate, 28% protein, 58% fat (< 10% saturated fat)] or an isocaloric high unrefined carbohydrate, low-fat diet [HC: 53% carbohydrate, 17% protein, 30% fat (< 10% saturated fat)] for 2 years. Both diets were combined with aerobic/resistance exercise (1 h, 3 days/week). Mood/well-being [Beck Depression Inventory (BDI), Spielberger State Anxiety Inventory (SAI), Profile of Mood States (POMS)], diabetes-related quality of life [Diabetes-39 (D-39)] and distress [Problem Areas in Diabetes (PAID) Questionnaire], and cognitive function were assessed during and post-intervention.

RESULTS

61 (LC: 33, HC: 28) participants completed the study. Weight loss was 9.1% after 12 months and 6.7% after 2 years with no difference between diet groups. There were no differences between the groups for the changes in any psychological health outcome (smallest p ≥ 0.19 for all time x diet interactions). Overtime, improvements in BDI, POMS [Total Mood Disturbance (TMD); four subscales], PAID, and D-39 (three subscales) scores occurred (p ≤ 0.05, time). Stepwise regression analysis showed improvements in BDI, POMS (TMD; two subscales), D-39, SAI, and PAID scores were significantly (p < 0.05) correlated with reductions in body weight and glycated hemoglobin.

CONCLUSION

In adults with obesity and T2DM, energy-restricted LC and HC diets produced comparable long-term improvements on a comprehensive range of psychological health outcomes. The findings suggest both diets can be used as a diabetes management strategy as part of a holistic lifestyle modification program without concern of negative effects on mental well-being or cognition.

TRIAL REGISTRATION

ACTRN12612000369820, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=362168&isReview=true . Data described in the manuscript, code book, and analytic code will not be made available because approval has not been granted by participants.

Diet, Obesity, and Depression: A Systematic Review

BACKGROUND

Obesity and depression co-occur in a significant proportion of the population. Mechanisms linking the two disorders include the immune and the endocrine system, psychological and social mechanisms. The aim of this systematic review was to ascertain whether weight loss through dietary interventions has the additional effect of ameliorating depressive symptoms in obese patients.

METHODS

We systematically searched three databases (Pubmed, Medline, Embase) for longitudinal clinical trials testing a dietary intervention in people with obesity and depression or symptoms of depression.

RESULTS

Twenty-four longitudinal clinical studies met the eligibility criteria with a total of 3244 included patients. Seventeen studies examined the effects of calorie-restricted diets and eight studies examined dietary supplements (two studies examined both). Only three studies examined people with a diagnosis of both obesity and depression. The majority of studies showed that interventions using a calorie-restricted diet resulted in decreases in depression scores, with effect sizes between ≈0.2 and ≈0.6. The results were less clear for dietary supplements.

CONCLUSIONS

People with obesity and depression appear to be a specific subgroup of depressed patients in which calorie-restricted diets might constitute a promising personalized treatment approach. The reduction of depressive symptoms may be related to immunoendocrine and psychosocial mechanisms.

Nutrition and behavioral health disorders: depression and anxiety

Suboptimal nutrition has been implicated in the underlying pathology of behavioral health disorders and may impede treatment and recovery. Thus, optimizing nutritional status should be a treatment for these disorders and is likely important for prevention. The purpose of this narrative review is to describe the global burden and features of depression and anxiety, and summarize recent evidence regarding the role of diet and nutrition in the prevention and management of depression and anxiety. Current evidence suggests that healthy eating patterns that meet food-based dietary recommendations and nutrient requirements may assist in the prevention and treatment of depression and anxiety. Randomized controlled trials are needed to better understand how diet and nutrition-related biological mechanisms affect behavioral health disorders, to assist with the development of effective evidence-based nutrition interventions, to reduce the impact of these disorders, and promote well-being for affected individuals.

An Almond-Based Low Carbohydrate Diet Improves Depression and Glycometabolism in Patients with Type 2 Diabetes through Modulating Gut Microbiota and GLP-1: A Randomized Controlled Trial

Background: Alow carbohydrate diet (LCD) is more beneficial for the glycometabolism in type 2 diabetes (T2DM) and may be effective in reducing depression. Almond, which is a common nut, has been shown to effectively improve hyperglycemia and depression symptoms. This study aimed to determine the effect of an almond-based LCD (a-LCD) on depression and glycometabolism, as well as gut microbiota and fasting glucagon-like peptide 1 (GLP-1) in patients with T2DM. Methods: This was a randomized controlled trial which compared an a-LCD with a low-fat diet (LFD). Forty-five participants with T2DM at a diabetes club and the Endocrine Division of the First and Second Affiliated Hospital of Soochow University between December 2018 to December 2019 completed each dietary intervention for 3 months, including 22 in the a-LCD group and 23 in the LFD group. The indicators for depression and biochemical indicators including glycosylated hemoglobin (HbA1c), gut microbiota, and GLP-1 concentration were assessed at the baseline and third month and compared between the two groups. Results: A-LCD significantly improved depression and HbA1c (p < 0.01). Meanwhile, a-LCD significantly increased the short chain fatty acid (SCFAs)-producing bacteria Roseburia, Ruminococcus and Eubacterium. The GLP-1 concentration in the a-LCD group was higher than that in the LFD group (p < 0.05). Conclusions: A-LCD could exert a beneficial effect on depression and glycometabolism in patients with T2DM. We speculate that the role of a-LCD in improving depression in patients with T2DM may be associated with it stimulating the growth of SCFAs-producing bacteria, increasing SCFAs production and GPR43 activation, and further maintaining GLP-1 secretion. In future studies, the SCFAs and GPR43 activation should be further examined.

Impact of male-only lifestyle interventions on men's mental health: A systematic review and meta-analysis

Despite rising mental health problems worldwide, engaging men to seek mental health support is challenging. Male-only lifestyle interventions have shown promise for improving men's physical health, but the overall impact of these programs on psychological outcomes is unclear. This review aimed to evaluate the impact of male-only lifestyle interventions on men's mental health and to identify if any study or intervention features were associated with effectiveness. A systematic literature search with no date restrictions was conducted across four databases and returned 15 946 citations. Nine studies were eligible for inclusion, representing 1427 participants. Risk of bias was generally low across studies, although none were specifically powered to detect changes in mental health. Overall, significant group-by-time effects were reported for 26% of mental health outcomes examined. In the fixed-effects meta-analyses, small-to-medium intervention effects were observed for mental health-related quality of life (SMD = 0.24), self-esteem (SMD = 0.51), and positive affect (SMD = 0.58). Insights into effective study or intervention features were limited because of the low number of heterogeneous studies. Although male-only lifestyle interventions have improved men's mental health in some circumstances, studies that are specifically powered to detect long-term changes are urgently required, particularly in groups with pre-existing mental health concerns.

Sex differences in subjectively reported symptoms of obstructive sleep apnea in community-dwelling adults with type 2 diabetes

BACKGROUND

Reports of sex differences in self-reported mood, sleep quality, daytime function, and excessive daytime sleepiness in people with obstructive sleep apnea (OSA) have been inconsistent. The purpose of this study was to investigate sex differences in these subjective sleep outcomes in participants with type 2 diabetes (T2D) either at high risk for OSA or diagnosed with OSA.

METHODS

Measures included OSA severity by apnea-hypopnea index (AHI) and self-reported questionnaires: Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), functional outcomes of sleep quality questionnaire (FOSQ), and the profile of mood states (POMS). Relevant individual, social, and health determinants were included as covariates.

RESULTS

A total of 350 participants with T2D [Mean A1C 8.0% (SD ±1.8)] had mean age 56.5 (SD ±10.5) and were balanced by sex (51% men) and race (60% white, 40% non-white). Reports of sleep quality and daytime function were worse in women than in men (p <0.05), whereas men had more severe OSA than women (p <0.05). In fully adjusted models, there was no moderation by sex in the relations between AHI and the sleep outcome measures. AHI showed a significant association with ESS but not PSQI, FOSQ, or POMS.

CONCLUSION

In participants with T2D at high risk for or diagnosed with OSA, excessive daytime sleepiness was independently associated with OSA severity, but not self-reported sleep quality, daytime function, or mood. While women reported worse outcomes associated with sleep, these outcomes were not associated with OSA severity.

Impact of weight loss interventions on patient-reported outcomes in overweight and obese adults with type 2 diabetes: a systematic review

Previous reviews explored weight loss-induced metabolic changes in overweight and obese adults with type 2 diabetes (T2D) but did not report on the impact on patient-reported outcomes (PROs). This systematic review investigated the effect of weight loss interventions on weight loss and PROs in overweight and obese adults with T2D. We searched three electronic databases from inception to March 2018 for randomised controlled trials (RCTs) of weight loss interventions in overweight and obese (according to BMI) adults aged ≥ 18 years reporting changes in PROs from baseline to at least one follow-up assessment during or post-intervention. One reviewer screened abstracts, performed data extraction, and conducted the narrative synthesis, with 25% cross-checking by a second reviewer. We extracted data relating to sample characteristics, intervention and comparison conditions, weight loss, and change in PROs. We identified 540 papers of which 23 met eligibility reporting on 19 RCTs. Four types of interventions (diet, surgery, pharmacological, and multi-component lifestyle interventions) significantly reduced weight. Weight loss was consistently associated with improvements in sexual and physical function across all intervention types, with diet and multi-component lifestyle interventions producing more substantial improvements than surgical or pharmacological interventions. Findings for other PROs, such as HRQOL and depressive symptoms, were inconsistent across studies and intervention types. The four weight loss interventions can be prescribed to engender weight loss in overweight and obese adults with T2D, with multi-component lifestyle interventions generating substantial improvements in physical and sexual function, perhaps due to the potency of exercise in improving PROs.

Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force

Historically, low-carbohydrate (CHO) and very-low-CHO diets have been used for weight loss. Recently, these diets have been promoted for type 2 diabetes (T2D) management. This scientific statement provides a comprehensive review of the current evidence base available from recent systematic reviews and meta-analyses on the effects of low-CHO and very-low-CHO diets on body weight, lipoprotein lipids, glycemic control, and other cardiometabolic risk factors. In addition, evidence on emerging risk factors and potential safety concerns of low-CHO and very-low-CHO diets, especially for high-risk individuals, such as those with genetic lipid disorders, was reviewed. Based on the evidence reviewed, low-CHO and very-low-CHO diets are not superior to other dietary approaches for weight loss. These diets may have advantages related to appetite control, triglyceride reduction, and reduction in the use of medication in T2D management. The evidence reviewed showed mixed effects on low-density lipoprotein cholesterol levels with some studies showing an increase. There was no clear evidence for advantages regarding effects on other cardiometabolic risk markers. Minimal data are available regarding long-term (>2 years) efficacy and safety. Clinicians are encouraged to consider the evidence discussed in this scientific statement when counseling patients on the use of low-CHO and very-low-CHO diets.

A review of dietary and microbial connections to depression, anxiety, and stress

Objective: Pre-clinical evidence suggests that the gastrointestinal microbiota contributes to mood and behavior disorders. Among humans, diet quality and patterns, which also impact the gastrointestinal microbiota, have been linked to depression, anxiety, and stress. This review summarizes findings from clinical studies using dietary intervention to improve depression, anxiety, or stress and the role the gastrointestinal microbiota may have in these disorders.Methods: A literature search was conducted using the keywords microbiome, microbiota, depression, anxiety, stress, diet, dietary pattern, diet quality, fiber, prebiotics, probiotics, and mood.Results: Mood was improved by enhancing diet quality. Fructooligosaccharide and galactooligosaccharide improved anxiety and depression in participants consuming ≥ 5 g/day. Additionally, bifidobacteria were enriched in subjects consuming ≥ 5 g/day. Probiotic consumption improved psychological or biological measures of depression, anxiety, or stress in individuals predisposed to a mood disorder. Probiotics suppressed biological markers of stress in healthy individuals in a strain-dependent manner.Discussion: High-quality diets, prebiotics, and probiotics may beneficially affect mood. Habitual diets rich in dietary fiber and omega-3-polyunsaturated fatty acids may be linked to reduced risk of developing symptoms of depression, anxiety, and stress; however, additional studies are necessary. Certain probiotics may enhance mood, but their influence on the gastrointestinal microbiota requires further investigation.

Lifestyle Modification Group for Lymphedema and Obesity Results in Significant Health Outcomes

This study investigated whether a lifestyle modification program that encouraged a ketogenic diet (KD) for participants with lymphedema and obesity would reduce weight and limb volume and improve quality of life. A total of 12 participants with lymphedema and obesity (mean body mass index = 38.38; SD = 7.02) were enrolled in a lifestyle modification group. The timespan from baseline data collection to 30-day follow-up was 18 weeks. Retention rate was 83.3%. Data were analyzed with repeated-measures ANOVA and Pearson correlation. Participants demonstrated statistically significant improvement in most outcome measures. Mean weight loss was 5.18 kg-F(4, 36) = 11.17; P < .001-or 4.8% of mean baseline weight. The average limb volume reduction was 698.9 ml-F(4, 36) = 9.4; P < .001-and was positively correlated with weight loss (r = 0.8; P = .005). There appeared to be a tendency for participants who used a KD (n = 6) to demonstrate superior results in most outcome measures compared with those who did not use the diet (n = 4), although the sample size of the 2 groups was too small to report definitive results. This lifestyle modification program provided insight into the possible value of a KD for obesity and lymphedema management.

Assessing quality of life in diabetes: II - Deconstructing measures into a simple framework

A growing number of instruments measuring diabetes-specific health-related quality of life (HRQOL) have been identified in previous systematic reviews, the most recent being published in 2008. The purpose of this paper is report on an updated systematic review of diabetes-specific HRQOL measures highlighting the time period 2006-2016; to deconstruct existing diabetes-specific HRQOL measures into a simple framework for evaluating the goodness-of-fit between specific research needs and instrument characteristics; and to present core characteristics of measures not yet reported in other reviews to further facilitate scale selection. Using the databases Medline, Pubmed, CINAHL, OVID Embase, and PsycINFO, we identified 20 diabetes-specific HRQOL measures that met our inclusion criteria. For each measure, we extracted eight core characteristics for our measurement selection framework. These characteristics include target population (type 1 vs. type 2), number and type of HRQOL dimensions measured and scored, type of score and calculation algorithm, sensitivity to change data reported in subsequent studies, number of survey items, approximate time length to complete, number of studies using the instrument in the past 10years, and specific languages instruments is translated. This report provides a way to compare and contrast existing diabetes-specific HRQOL measures to aid in appropriate scale selection and utilization.

Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes

OBJECTIVE

Nutrition therapy is an integral part of self-management education in patients with type 2 diabetes. Carbohydrates with a low glycemic index are recommended, but the ideal amount of carbohydrate in the diet is unclear. We performed a meta-analysis comparing diets containing low to moderate amounts of carbohydrate (LCD) (energy percentage below 45%) to diets containing high amounts of carbohydrate (HCD) in subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We systematically reviewed Cochrane library databases, EMBASE, and MEDLINE in the period 2004-2014 for guidelines, meta-analyses, and randomized trials assessing the outcomes HbA1c, BMI, weight, LDL cholesterol, quality of life (QoL), and attrition.

RESULTS

We identified 10 randomized trials comprising 1376 participants in total. In the first year of intervention, LCD was followed by a 0.34% lower HbA1c (3.7 mmol/mol) compared with HCD (95% CI 0.06 (0.7 mmol/mol), 0.63 (6.9 mmol/mol)). The greater the carbohydrate restriction, the greater the glucose-lowering effect (R=-0.85, p<0.01). At 1 year or later, however, HbA1c was similar in the 2 diet groups. The effect of the 2 types of diet on BMI/body weight, LDL cholesterol, QoL, and attrition rate was similar throughout interventions.

LIMITATIONS

Glucose-lowering medication, the nutrition therapy, the amount of carbohydrate in the diet, glycemic index, fat and protein intake, baseline HbA1c, and adherence to the prescribed diets could all have affected the outcomes.

CONCLUSIONS

Low to moderate carbohydrate diets have greater effect on glycemic control in type 2 diabetes compared with high-carbohydrate diets in the first year of intervention. The greater the carbohydrate restriction, the greater glucose lowering, a relationship that has not been demonstrated earlier. Apart from this lowering of HbA1c over the short term, there is no superiority of low-carbohydrate diets in terms of glycemic control, weight, or LDL cholesterol.

The Effects of Low-Carbohydrate Diets on Psychosocial Outcomes in Obesity/Overweight: A Systematic Review of Randomized, Controlled Studies

Background: Little is known about the relative psychosocial effects of carbohydrate reduction in comparison to other weight-loss diets in subjects receiving treatment for obesity/overweight. We, therefore, set out to conduct a systematic review of the psychosocial outcomes of such patients, treated by means of either a low-carbohydrate diet or an isocaloric diet of other macronutrient composition. Methods: Literature searches, study selection, method development, and quality appraisal were performed independently by two authors, and data were synthesized using a narrative approach, in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Results: Eight randomized controlled studies met the inclusion criteria, and their subsequent analysis revealed that improvements in psychological and social outcomes do occur during short- and long-term weight loss programmes, but that low-carbohydrate diets have no greater effect on psychosocial outcomes when compared to diets of different macronutrient composition at either short- or long-term follow-up (one-year). However, the lack of studies with longer duration follow-up, and the absence of data in the adolescent population limit the generalizability of our findings. Conclusion: The short- and long-term improvements in psychosocial outcomes seen in patients undergoing weight-loss treatment appear to be independent of the macronutrient composition of their diet.