Selective carbohydrate or protein restriction: Effects on subsequent food intake and cravings

The Data Behind Popular Diets for Weight Loss

Both scientific evidence and popular diet trends have sought to identify the ideal diet for weight loss with strategies focused on either restricting carbohydrates or fat. While there is a strong physiologic rationale for either carbohydrate restriction or fat restriction to achieve a calorie deficit needed for weight loss, evidence from randomized controlled trials suggest either type of diet is effective for weight loss. The level of adherence, rather than macronutrient content, is the driver of successful weight loss.

The Psychology of Food Cravings: the Role of Food Deprivation

PURPOSE OF REVIEW

Dieting is often blamed for causing food cravings. Such diet-induced cravings may be mediated by physiological (e.g., nutritional deprivation) or psychological (e.g., ironic effects of food thought suppression) mechanisms. However, this notion is often based on cross-sectional findings and, thus, the causal role of food deprivation on food cravings is unclear.

RECENT FINDINGS

Experimental studies suggest that a short-term, selective food deprivation seems to indeed increase cravings for the avoided foods. However, experimental studies also show that food craving can be understood as a conditioned response that, therefore, can also be unlearned. This is supported by intervention studies which indicate that long-term energy restriction results in a reduction of food cravings in overweight adults. Dieting's bad reputation for increasing food cravings is only partially true as the relationship between food restriction and craving is more complex. While short-term, selective food deprivation may indeed increase food cravings, long-term energy restriction seems to decrease food cravings, suggesting that food deprivation can also facilitate extinction of conditioned food craving responses.

Predicting Weight Loss Using Psychological and Behavioral Factors: The POUNDS LOST Trial

CONTEXT

Eating habits and food craving are strongly correlated with weight status. It is currently not well understood how psychological and behavioral factors influence both weight loss and weight regain.

OBJECTIVE

To examine the associations between psychological and behavioral predictors with weight changes and energy intake in a randomized controlled trial on weight loss.

DESIGN AND SETTING

The Prevention of Obesity Using Novel Dietary Strategies is a dietary intervention trial that examined the efficacy of 4 diets on weight loss over 2 years. Participants were 811 overweight (body mass index, 25-40.9 kg/m2; age, 30-70 years) otherwise healthy adults.

RESULTS

Every 1-point increase in craving score for high-fat foods at baseline was associated with greater weight loss (-1.62 kg, P = .0004) and a decrease in energy intake (r = -0.10, P = .01) and fat intake (r = -0.16, P < .0001) during the weight loss period. In contrast, craving for carbohydrates/starches was associated with both less weight loss (P < .0001) and more weight regain (P = .04). Greater cognitive restraint of eating at baseline was associated with both less weight loss (0.23 kg, P < .0001) and more weight regain (0.14 kg, P = .0027), whereas greater disinhibition of eating was only associated with more weight regain (0.12 kg, P = .01).

CONCLUSIONS

Craving for high-fat foods is predictive of greater weight loss, whereas craving for carbohydrates is predictive of less weight loss. Cognitive restraint is predictive of less weight loss and more weight regain. Interventions targeting different psychological and behavioral factors can lead to greater success in weight loss.

Changes in Food Cravings and Eating Behavior after a Dietary Carbohydrate Restriction Intervention Trial

Compared to low-fat diets, low-carbohydrate (CHO) diets cause weight loss (WL) over a faster time frame; however, it is unknown how changes in food cravings and eating behavior contribute to this more rapid WL in the early phases of dieting. We hypothesized that reductions in food cravings and improved eating behaviors would be evident even after a relatively short (4-week) duration of CHO-restriction, and that these changes would be associated with WL. Adult participants (n = 19, 53% males, mean ± SD: BMI = 34.1 ± 0.8 kg/m²; age 40.6 ± 1.9 years) consumed a CHO-restricted diet (14% CHO, 58% fat, 28% protein) for 4 weeks. Before and after the intervention, specific and total cravings were measured with the Food Craving Inventory (FCI) and eating behaviors assessed with the Three-Factor Eating questionnaire. Food cravings were significantly reduced at week 4, while women had significantly greater reductions in sweet cravings than men. Dietary restraint was significantly increased by 102%, while disinhibiton and hunger scores were reduced (17% and 22%, respectively, p < 0.05). Changes in cravings were unrelated to changes in body weight except for the change in high-fat cravings where those who lost the most weight experienced the least reductions in fat cravings (r = −0.458, p = 0.049). Changes in dietary restraint were inversely related to several FCI subscales. A short-term, low-CHO diet was effective in reducing food cravings. These data suggest that in subjects that have successfully lost weight on a low-CHO diet, those who craved high-fat foods at the onset were able to satisfy their cravings—potentially due to the high-fat nature of this restricted diet.

Reductions in food cravings are similar with low-fat weight loss diets differing in protein and carbohydrate in overweight and obese adults with type 2 diabetes: A randomized clinical trial

Food cravings are common in type 2 diabetes (T2D). Higher-protein diets are effective in improving satiety but their effect on cravings is unclear. It was hypothesized that a high protein (HP) diet would provide greater reductions in cravings than an isocaloric higher-carbohydrate diet (HC). In a randomized controlled trial, 61 adults (54% males) with T2D (means ± SD: BMI 34.3 ± 5.1 kg/m²; aged 55 ± 8 years) consumed either a HP diet (mean across study: 29% protein, 34% carbohydrate, 31% fat) or an isocaloric HC diet (21%:48%:24%) for 12-weeks each of weight loss (WL) and weight maintenance (WM). The Food Craving Inventory (FCI), measuring types of foods craved and the General Food Craving Questionnaires measuring traits (G-FCQ-T) and states (G-FCQ-S) were assessed at Weeks 0, 12 and 24. Weight changes were similar between groups (means ± SEM: WL: -7.8 ± 0.6 kg, WM: -0.6 ± 0.4 kg). No group effects or group x time interactions were found for any outcome (P ≥ .07). Independent of group, all food cravings (except carbohydrates) and G-FCQ-T subscales decreased over the 24-week study (P ≤ .04) with sweets and fast food cravings, loss of control and emotional cravings reducing following WL (P ≤ .03). Obsessive preoccupation with food decreased following both phases (WL: P = .03; WM: P = .001). Weight was associated with several FCI subscales (r ≥ 0.24, P ≤ .04). In conclusion, both the HP and HC diets provided significant reductions in food cravings after similar weight losses which were maintained when weight was stabilized.

Independent associations and effect modification between lifetime substance use and recent mood disorder diagnosis with household food insecurity

Poor mental health and substance use are associated with food insecurity, however, their potential combined effects have not been studied. This study explored independent associations and effect modification between lifetime substance use and mood disorder in relation to food insecurity. Poisson regression analysis of data from British Columbia respondents (n = 13,450; 12 years+) in the 2007/08 Canadian Community Health Survey was conducted. Measures included The Household Food Security Survey Module (7.3% food insecure), recent diagnosis of a mood disorder (self-reported; 9.5%), lifetime use of cannabis, cocaine/crack, ecstasy, hallucinogens, and speed, any lifetime substance use, sociodemographic covariates, and the interaction terms of mood disorder by substance. For those with recent diagnosis of a mood disorder the prevalence of lifetime substance use ranged between 1.2 to 5.7% and were significantly higher than those without recent mood disorder diagnosis or lifetime use of substances (p’s < 0.05). For respondents with a recent mood disorder diagnosis or who used cannabis, food insecurity prevalence was higher compared to the general sample (p < 0.001); prevalence was lower for cocaine/crack use (p < 0.05). Significant effect modification was found between mood disorder with cannabis, ecstasy, hallucinogen and any substance use over the lifetime (PRs 0.51 to 0.64, p’s 0.022 to 0.001). Independent associations were found for cocaine/crack and speed use (PRs 1.68, p’s < 0.001) and mood disorder (PRs 2.02, p’s < 0.001). Based on these findings and the existing literature, future study about coping and resilience in the context of substance use, mental health, and food insecurity may lead to the development of relevant interventions aimed at mental well-being and food security.

Effects of Chocolate Deprivation on Implicit and Explicit Evaluation of Chocolate in High and Low Trait Chocolate Cravers

Diet failures are often attributed to an increase in cravings for attractive foods. However, accumulating evidence shows that food cravings actually decrease during energy-restricting weight-loss interventions. The current study aimed at elucidating possible mechanisms that may explain how and under which circumstances food cravings in- or decrease during dieting. Specifically, decreases in food cravings during weight-loss diets may be due to effects of energy restriction (homeostatic changes) and to effects of avoiding specific foods (hedonic changes). Thus, we used a selective, hedonic deprivation (i.e., restricting intake of a specific food in the absence of an energy deficit) that precludes homeostatic changes due to energy restriction. Furthermore, interindividual differences in food craving experiences might affect why some individuals are more prone to experience cravings during dieting than others. Thus, we investigated whether a selective deprivation of chocolate would in- or decrease craving and implicit preference for chocolate as a function of trait-level differences in chocolate craving. Participants with high and low trait chocolate craving (HC, LC) refrained from consuming chocolate for 2 weeks but otherwise maintained their usual food intake. Both groups underwent laboratory assessments before and after deprivation, each including explicit (i.e., state chocolate craving) and implicit measures (i.e., Single Category Implicit Association Test, SC-IAT; Affect Misattribution Procedure, AMP). Results showed that hedonic deprivation increased state chocolate craving in HCs only. HCs also showed more positive implicit attitudes toward chocolate than LCs on the SC-IAT and the AMP irrespective of deprivation. Results help to disambiguate previous studies on the effects of dieting on food cravings. Specifically, while previous studies showed that energy-restricting diets appear to decrease food cravings, the current study showed that a selective, hedonic deprivation in the absence of an energy deficit increases food cravings. However, this effect can only be observed for individuals with high trait craving levels. Thus, if attractive foods are strictly avoided through a selective deprivation, HCs are at risk to experience craving bouts in the absence of an energy deficit. As implicit preference was unaffected by chocolate deprivation, strong implicit preference for chocolate likely characterize a stable mechanism that drives consumption in HCs.

Seasonal Bushmeat Hunger in the Congo Basin

Unlike the Sudano-sahelian regions, which are confronted to severe periods of food shortage, tropical rainforests are known to provide a constant supply of a great diversity of food resources that mitigates the risk of food starvation for omnivorous humans. Nevertheless, several African forest ethnic groups suffer from a seasonal hunger induced by depletion in the procurement of bushmeat, which is a food of paramount importance. Although the diet remains well balanced and meets all the nutritional needs, the bushmeat cravers loose weight and experience a stress that affects their well-being. Bushmeat hunger is a psychocultural form of hunger that generates several mental disorders. We present results from nutritional anthropology studies carried out among various Congo Basin forest peoples, which regularly suffer from bushmeat hunger. We expose the physiological risks that result from this psychological unrest, we argue that this type of unsatisfied compiling desire for meat should be considered as a factor of food insecurity and we conclude on its incidence on bushmeat trade. The immoderate craving for bushmeat compromises the attempts to replace bushmeat by other sources of meat and is a persisting obstacle to conservation initiatives that fail to take the psychocultural values of bushmeat into consideration.

Association of moderate and severe food insecurity with suicidal ideation in adults: national survey data from three Canadian provinces

PURPOSE

Although the important public health issues of food insecurity and suicide may be interconnected, they are rarely studied. Using data from a national survey, we examined whether household food insecurity was associated with suicidal ideation after adjusting for relevant covariates.

METHODS

We examined cross-sectional data from three Canadian provinces (n = 5,270) that were derived from the 2007 Canadian Community Health Survey and included adults (18+ years). Suicidal ideation was based on affirmative response to the question of whether or not the participant had seriously considered committing suicide in the previous 12 months. The Household Food Security Survey Module provided measures of moderate (indication of compromise in quality and/or quantity of food consumed) and severe (indication of reduced food intake and disrupted eating patterns) food insecurity status. Logistic regression determined associations between food insecurity and suicidal ideation with adjustment for demographics, body mass index, and presence of a mood disorder.

RESULTS

There were differences in the proportion experiencing suicide ideation according to moderate (14.7 vs 10.0 % without suicide ideation) and severe (16.4 vs 7.1 % without suicide ideation) food security (p < 0.001). With covariate adjustment, suicidal ideation was significantly associated with moderate (adjusted OR = 1.32, 95 % CI 1.06-1.64) and severe (adjusted OR = 1.77, 95 % CI 1.42-2.23) food insecurity.

CONCLUSIONS

The findings of a robust association between food insecurity and suicidal ideation suggest that interventions targeted at food security may reduce suicide-related morbidity and mortality. Longitudinal investigations that examine various dimensions of food insecurity will advance understanding of etiological pathways involved in food insecurity and suicide.

Dietary variety is inversely associated with body adiposity among US adults using a novel food diversity index

BACKGROUND

Consuming a variety (vs. monotony) of energy-poor, nutrient-dense foods may help individuals adhere to dietary patterns favorably associated with weight control.

OBJECTIVE

The objective of this study was to examine whether greater healthful food variety quantified using the US Healthy Food Diversity (HFD) index favorably influenced body adiposity.

METHODS

Men and nonpregnant, nonlactating women aged ≥20 y with two 24-h recalls from the cross-sectional NHANES 2003-2006 (n = 7470) were included in this study. Dietary recalls were merged with the MyPyramid Equivalent database to generate the US HFD index, which ranges from 0 to ∼1, with higher scores indicative of diets with a higher number and proportion of healthful foods. Multiple indicators of adiposity including BMI, waist-to-height ratio, android-to-gynoid fat ratio, fat mass index (FMI), and percentage body fat were assessed across US HFD index quintiles. ORs and 95% CIs were computed with use of multivariable logistic regression (SAS v. 9.3).

RESULTS

The US HFD index was inversely associated with most adiposity indicators in both sexes. After multivariable adjustment, the odds of obesity, android-to-gynoid ratio >1, and high FMI were 31-55% lower (P-trend < 0.01) among women in quintile 5 vs. quintile 1 of the US HFD index. Among men, the odds of obesity, waist-to-height ratio ≥0.5, and android-to-gynoid ratio >1 were 40-48% lower (P-trend ≤ 0.01) in quintile 5 vs. quintile 1 of the US HFD index.

CONCLUSIONS

Higher US HFD index values were inversely associated with indicators of body adiposity in both sexes, indicating that greater healthful food variety may protect against excess adiposity. This study explicitly recognizes the potential benefits of dietary variety in obesity management and provides the foundation to support its ongoing evaluation.

Relationship of cravings with weight loss and hunger. Results from a 6 month worksite weight loss intervention

We examined the association of food cravings with weight loss and eating behaviors in a lifestyle intervention for weight loss in worksites. This research was part of a randomized controlled trial of a 6-month weight loss intervention versus a wait-listed control in 4 Massachusetts worksites. The intervention emphasized reducing energy intake by adherence to portion-controlled menu suggestions, and assessments were obtained in 95 participants at baseline and 6 months including non-fasting body weight, food cravings (Craving Inventory and Food Craving Questionnaire for state and trait) and the eating behavior constructs restraint, disinhibition and hunger (Eating Inventory). There were statistically significant reductions in all craving variables in the intervention group compared to the controls. Within the intervention group, changes in craving-trait were significantly associated with weight loss after controlling for baseline weight, age, gender and worksite. However, in a multivariate model with craving-trait and eating behaviors (restraint, disinhibition and hunger), hunger was the only significant predictor of weight change. In contrast to some previous reports of increased food cravings with weight loss in lifestyle interventions, this study observed a broad reduction in cravings associated with weight loss. In addition, greater reductions in craving-trait were associated with greater weight change, but craving-trait was not a significant independent correlate of weight change when hunger was included in statistical models. Studies are needed to examine the effectiveness of hunger suppressing versus craving-suppressing strategies in lifestyle interventions for obesity.

Diet type and changes in food cravings following weight loss: findings from the POUNDS LOST Trial

Few well-controlled trials have evaluated the effects that macronutrient composition has on changes in food cravings during weight loss treatment. The present study, which was part of the Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST) trial, investigated whether the fat and protein content of four different diets affected changes in specific food cravings in overweight and obese adults. A sample of 811 adults were recruited across two clinical sites, and each participant was randomly assigned to one of four macronutrient prescriptions: 1) low fat (20% of energy), average protein (15% of energy); 2) moderate fat (40%), average protein (15%); 3) low fat (20%), high protein (25%); 4) moderate fat (40%), high protein (25%). With few exceptions, the type of diet that participants were assigned did not differentially affect changes in specific food cravings. Participants assigned to the high-fat diets, however, had reduced cravings for carbohydrates at month 12 (p<0.05) and fruits and vegetables at month 24. Also, participants assigned to high-protein diets had increased cravings for sweets at month 6 and month 12 (ps<0.05). Participants in all four dietary conditions reported significant reductions in food cravings for specific types of foods (i.e., high fat foods, fast food fats, sweets, and carbohydrates/starches; all ps<0.05). Cravings for fruits and vegetables, however, were increased at month 24 (p<0.05). Calorically restricted diets (regardless of their macronutrient composition) yielded significant reductions in cravings for fats, sweets, and starches whereas cravings for fruits and vegetables were increased.

Feed-forward mechanisms: addiction-like behavioral and molecular adaptations in overeating

Food reward, not hunger, is the main driving force behind eating in the modern obesogenic environment. Palatable foods, generally calorie-dense and rich in sugar/fat, are thus readily overconsumed despite the resulting health consequences. Important advances have been made to explain mechanisms underlying excessive consumption as an immediate response to presentation of rewarding tastants. However, our understanding of long-term neural adaptations to food reward that oftentimes persist during even a prolonged absence of palatable food and contribute to the reinstatement of compulsive overeating of high-fat high-sugar diets, is much more limited. Here we discuss the evidence from animal and human studies for neural and molecular adaptations in both homeostatic and non-homeostatic appetite regulation that may underlie the formation of a "feed-forward" system, sensitive to palatable food and propelling the individual from a basic preference for palatable diets to food craving and compulsive, addiction-like eating behavior.

Meal timing and composition influence ghrelin levels, appetite scores and weight loss maintenance in overweight and obese adults

BACKGROUND

Although dietary restriction often results in initial weight loss, the majority of obese dieters fail to maintain their reduced weight. Diet-induced weight loss results in compensatory increase of hunger, craving and decreased ghrelin suppression that encourage weight regain. A high protein and carbohydrate breakfast may overcome these compensatory changes and prevent obesity relapse.

METHODS

In this study 193 obese (BMI 32.2±1.0kg/m(2)), sedentary non diabetic adult men and women (47±7years) were randomized to a low carbohydrate breakfast (LCb) or an isocaloric diet with high carbohydrate and protein breakfast (HCPb). Anthropometric measures were assessed every 4weeks. Fasting glucose, insulin, ghrelin, lipids, craving scores and breakfast meal challenge assessing hunger, satiety, insulin and ghrelin responses, were performed at baseline, after a Diet Intervention Period (Week 16) and after a Follow-up Period (Week 32).

RESULTS

At Week 16, groups exhibited similar weight loss: 15.1±1.9kg in LCb group vs. 13.5±2.3kg in HCPb group, p=0.11. From Week 16 to Week 32, LCb group regained 11.6±2.6kg, while the HCPb group lost additional 6.9±1.7kg. Ghrelin levels were reduced after breakfast by 45.2% and 29.5% following the HCPb and LCb, respectively. Satiety was significantly improved and hunger and craving scores significantly reduced in the HCPb group vs. the LCb group.

CONCLUSION

A high carbohydrate and protein breakfast may prevent weight regain by reducing diet-induced compensatory changes in hunger, cravings and ghrelin suppression. To achieve long-term weight loss, meal timing and macronutrient composition must counteract these compensatory mechanisms which encourage weight regain after weight loss.

Daily consumption of individual snack foods decreases their reinforcing value

The reinforcing value of food is one factor that influences energy intake. The purpose of this study was to determine if the reinforcing value of highly liked snack foods could be modified by restriction or daily intake of individual preferred foods in the absence of changes in total energy intake. Food reinforcement was tested at baseline and after each of two, two-week phases. During the restriction phase, participants did not eat a target food or closely related foods while during the daily intake phase, participants consumed a 200-300 kcal portion of the target food daily. The reinforcing value of the target food significantly decreased after two weeks of daily intake. Restriction did not change food reinforcement. These data suggest that eating a portion of a highly palatable food every day decreases its reinforcing value. Implications for weight control are discussed.

Low-carbohydrate, high-protein diets revisited

PURPOSE OF REVIEW

There has been continued interest in the physiological, nutritional and clinical aspects of low-carbohydrate diets. This review will discuss the effects on appetite regulation, metabolic parameters, body weight and body composition, the role of glycemic index and glycemic load, as well as long-term outcomes.

RECENT FINDINGS

Low-carbohydrate, high-protein diets appear to improve satiety through their actions on measures of adiposity and gut peptides that influence appetite and caloric intake. Specific macronutrients such as low glycemic index carbohydrates and dietary protein impact appetite, calorie intake and metabolic parameters independent of weight loss. Long-term data, however, continue to support that total weight loss among low-carbohydrate dieters is not significantly different from low-fat dieters. The long-term safety of low-carbohydrate, high-protein diets on cardiovascular disease risk remains undetermined.

SUMMARY

Low-carbohydrate, high-protein diets may be an effective choice for weight loss, enhanced satiety and improved metabolic parameters.

The psychology of food craving

Cravings are hedonic responses to food, characterised by their intensity and their specificity. Food cravings are extremely common, reported by the majority of young adults. They are closely associated with liking but not synonymous with increased intake. Structured interviews and prospective incident accounts of food cravings have succeeded in revealing a richness of information about their character, their antecedents and their consequences. In addition, laboratory investigations are adding to what is being learned from field and clinical studies. Taking dieting as an example of an assumed influence on food craving, the outcomes of cross-sectional studies are mixed and unconvincing. Prospective and experimental research shows a clearer relationship. Dieting or restrained eating generally increase the likelihood of food craving while fasting makes craving, like hunger, diminish. Attempted restriction or deprivation of a particular food is associated with an increase in craving for the unavailable food. This relationship suggests a variety of underlying cognitive, conditioning and emotional processes, of which ironic cognitive processes, conditioned cue reactivity and dysphoric mood are prominent. Food cravings may also be self-attributions, accounting for why a highly-palatable but self-restricted food is (over-)consumed. Overall, the popularised account of cravings as elicited by specific nutritional need is having to give way to a more subtle and complex appreciation of human eating behaviour.