The impact and utility of very low-calorie diets: the role of exercise and protein in preserving skeletal muscle mass

Nutritional status in the era of highly effective CFTR modulators

Advances in cystic fibrosis (CF) diagnostics and therapeutics have led to improved health and longevity, including increased body weight and decreased malnutrition in people with CF. Highly effective CFTR modulator therapies (HEMT) are associated with increased weight through a variety of mechanisms, accelerating trends of overweight and obesity in the CF population. Higher body mass index (BMI) is associated with improved pulmonary function in CF, yet the incremental improvement at overweight and obese BMIs is not clear. Improvements in pulmonary health with increasing BMI are largely driven by increases in fat-free mass (FFM), and impact of HEMT on FFM is uncertain. While trends toward higher weight and BMI are generally seen as favorable in CF, the increased prevalence of overweight and obesity has raised concern for potential risk of traditional age- and obesity-related comorbidities. Such comorbidities, including impaired glucose tolerance, hypertension, cardiac disease, hyperlipidemia, fatty liver, colon cancer, and obstructive sleep apnea, may occur on top of pre-existing CF-related comorbidities. CF nutrition recommendations are evolving in the post-modulator era to more individualized approaches, in contrast to prior blanket high-fat, high-calorie prescriptions for all. Ultimately, it will be essential to redefine goals for optimal weight and nutritional status to allow for holistic health and aging in people with CF.

Effects of Very Low-Calorie Diet versus Roux-en-Y Gastric Bypass Surgery on Body Composition in Patients with Obesity

Roux-en-Y gastric bypass (RYGB) is the most effective treatment for severe obesity. A very low-calorie diet (VLCD) is another effective dietary intervention to treat obesity. This study evaluated the effect of a VLCD versus RYGB on weight reduction, changes in body composition and the resolution of comorbidities during a 12-week period. Individuals with obesity at the obesity clinic, Ramathibodi Hospital, Mahidol University, Thailand with a body mass index (BMI) ≥ 37.5 kg/m2 or ≥32.5 kg/m2 with obesity-related complications were recruited. Treatment options, either RYGB or VLCD, were assigned depending on patients' preferences and physicians' judgment. The analysis included 16 participants in the RYGB group and 15 participants in the VLCD group. Baseline characteristics were similar between groups; nevertheless, the participants in the VLCD group were significantly younger than those in the RYGB group. The number of patients with type 2 diabetes (T2D) was slightly higher in the RYGB group (43.8% vs. 33.3%, p = 0.552). Additionally, patients in the RYGB group had a longer duration of T2D and were treated with anti-diabetic agents, while VLCD patients received only lifestyle modifications. At 12 weeks, total and percentage weight loss in the RYGB and VLCD groups, respectively, were as follows: -17.6 ± 6.0 kg vs. -15.6 ± 5.1 kg (p = 0.335) and -16.2% ± 4.3% vs. -14.1% ± 3.6% (p = 0.147). Changes in biochemical data and the resolution of comorbidities were similar between the groups at 12 weeks. A 12-week VLCD resulted in similar weight loss and metabolic improvement compared with RYGB. Large-scale studies with long follow-up periods are needed to elucidate whether VLCD is a viable alternative treatment to bariatric surgery.

Skeletal muscle dysfunction with advancing age

As a result of advances in medical treatments and associated policy over the last century, life expectancy has risen substantially and continues to increase globally. However, the disconnect between lifespan and 'health span' (the length of time spent in a healthy, disease-free state) has also increased, with skeletal muscle being a substantial contributor to this. Biological ageing is accompanied by declines in both skeletal muscle mass and function, termed sarcopenia. The mechanisms underpinning sarcopenia are multifactorial and are known to include marked alterations in muscle protein turnover and adaptations to the neural input to muscle. However, to date, the relative contribution of each factor remains largely unexplored. Specifically, muscle protein synthetic responses to key anabolic stimuli are blunted with advancing age, whilst alterations to neural components, spanning from the motor cortex and motoneuron excitability to the neuromuscular junction, may explain the greater magnitude of function losses when compared with mass. The consequences of these losses can be devastating for individuals, their support networks, and healthcare services; with clear detrimental impacts on both clinical (e.g., mortality, frailty, and post-treatment complications) and societal (e.g., independence maintenance) outcomes. Whether declines in muscle quantity and quality are an inevitable component of ageing remains to be completely understood. Nevertheless, strategies to mitigate these declines are of vital importance to improve the health span of older adults. This review aims to provide an overview of the declines in skeletal muscle mass and function with advancing age, describes the wide-ranging implications of these declines, and finally suggests strategies to mitigate them, including the merits of emerging pharmaceutical agents.

Enhanced protein intake on maintaining muscle mass, strength, and physical function in adults with overweight/obesity: A systematic review and meta-analysis

BACKGROUND & AIMS

Weight loss in individuals with obesity and overweight leads to metabolic and health benefits but also poses the risk of muscle mass reduction. This systematic review and meta-analysis of randomized controlled trials aims to determine the initial protein amount necessary for achieving weight loss while maintaining muscle mass, strength, and physical function in adults with overweight and obesity.

METHODS

Relevant literature databases, including Medical Literature Analysis and Retrieval System Online (Medline), Excerpta Medica (Embase), the Cumulative Index to Nursing and Allied Health Literature (CINHAL), and Web of Science, were electronically searched up to 15 March 2023. We examined the effect of additional protein intake on muscle mass, strength, and physical function in adults with overweight or obesity targeting weight loss. The risk of bias was assessed using the Cochrane RoB 2.0 tool. Results were synthesized using standardized mean differences (SMD) and 95% confidence intervals (CI) via a random-effects model.

RESULTS

Forty-seven studies (n = 3218) were included. In the muscle mass analysis, twenty-eight trials with 1989 participants were encompassed. Results indicated that increased protein intake significantly prevents muscle mass decline in adults with overweight or obesity aiming for weight loss (SMD 0.75; 95% CI 0.41 to 1.10; p < 0.001). Enhanced protein intake did not significantly prevent decreases in muscle strength and physical function. An intake exceeding 1.3 g/kg/day is anticipated to increase muscle mass, while an intake below 1.0 g/kg/day is associated with a higher risk of muscle mass decline. The risk of bias in studies regarding muscle mass ranged from low to high.

CONCLUSIONS

Adults with overweight or obesity and aim for weight loss can more effectively retain muscle mass through higher protein intake, as opposed to no protein intake enhancement.

The effect of obesity pharmacotherapy on body composition, including muscle mass

Obesity pharmacotherapy represents a promising approach to treating obesity and may provide benefits beyond weight loss alone. Maintaining or even increasing muscle mass during weight loss is important to overall health, metabolic function and weight loss maintenance. Drugs such as liraglutide, semaglutide, tirzepatide, and naltrexone/bupropion have shown significant weight loss effects, and emerging evidence suggests they may also have effects on body composition, particularly a positive influence on muscle mass. However, further research is needed to fully understand the mechanism of action of these drugs and their effects on muscle mass. Clinicians should consider these factors when developing an obesity treatment plan for an individual patient.

Sarcopenic obesity in older adults: a clinical overview

Sarcopenic obesity is characterized by a concurrent decline in muscle mass and function, along with increased adipose tissue. Sarcopenic obesity is a growing concern in older adults owing to significant health consequences, including implications for mortality, comorbidities and risk of developing geriatric syndromes. A 2022 consensus statement established a new definition and diagnostic criteria for sarcopenic obesity. The pathophysiology of this condition involves a complex interplay between muscle, adipose tissue, hormonal changes, inflammation, oxidative stress and lifestyle factors, among others. Sarcopenic obesity is treated with a range of management approaches, such as lifestyle interventions, exercise, nutrition and medical therapies. Emerging therapies that were developed for treating other conditions may be relevant to sarcopenic obesity, including novel pharmacological agents and personalized approaches such as precision medicine. In this Review, we synthesize the current knowledge of the clinical importance of sarcopenic obesity, its assessment and diagnosis, along with current and emerging management strategies.

Quality of life, household income, and dietary habits are associated with the risk of sarcopenia among the Chinese elderly

BACKGROUND

Health-related quality of life (HRQoL), which can be influenced by various aspects, especially socioeconomic status and lifestyle, has been identified as an important predictor of the prognosis of older adults. Dietary habit, a major part of lifestyle, can affect the nutritional status, which is closely correlated with the development of geriatric syndromes in the elderly.

AIMS

The aim of the study was to examine the association of HRQoL, socioeconomic status, and lifestyle with the risk and severity of sarcopenia, a geriatric syndrome characterized by progressive loss of skeletal muscle mass, strength and function.

METHODS

A cross-sectional retrospective study with 2877 participants aged ≥65 years was performed. HRQoL was assessed using EuroQoL Five Dimensions questionnaire. Socioeconomic status was assessed by the educational attainment, occupation, and household income. Lifestyle was assessed using 12 items closely related to Chinese living habits. The information of daily dietary habits including tea, alcohol, type of diet, and volume of drinking water were collected. The associations of HRQoL, socioeconomic status, and lifestyle with the risk of sarcopenia were examined by multivariate regression logistical analysis. The potential causal role of age, body mass index, and waist circumference in the effect of HRQoL on sarcopenia risk was analyzed by causal mediation analysis.

RESULTS

High HRQoL [adjusted odds ratio (OR) =0.85, 95% confidence interval (CI) =0.69-0.95, P=0.034] and household income levels (adjusted OR =0.74, 95% CI =0.57-0.95, P=0.019) were inversely associated with the risk of sarcopenia. Meanwhile, more consumption of spicy food (adjusted OR =1.34, 95% CI =1.09-1.81, P =0.037) and occasionally drinking (adjusted OR =1.46, 95% CI =1.07-2.00, P =0.016, as compared to those never drinking) were associated with higher risk of sarcopenia, while skipping breakfast occasionally (adjusted OR =0.37, 95% CI =0.21-0.64, P <0.001, as compared to those eating breakfast every day) and less consumption of salt (adjusted OR =0.71, 95% CI =0.52-0.96, P =0.026, as compared to those consuming high amount of salt) were associated with lower risk of sarcopenia. Further causal mediation analysis aimed to explore how much age, body mass index, and waist circumference might explain the effect of HRQoL on the risk of sarcopenia showed that the estimated proportion that mediated the effect of HRQoL on the risk of sarcopenia by age was 28.0%.

CONCLUSIONS

In summary, our findings demonstrate that low levels of HRQoL and household income, more intake of salt and spicy food, and occasional intake of alcohol are correlated with higher risk of sarcopenia, while skipping breakfast occasionally is associated with lower risk of sarcopenia in a Chinese population of older adults.