Surabhi Bhutani

Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults

BACKGROUND The ability of modified alternate-day fasting (ADF; ie, consuming 25% of energy needs on the fast day and ad libitum food intake on the following day) to facilitate weight loss and lower vascular disease risk in obese individuals remains unknown. OBJECTIVE This study examined the effects of ADF that is administered under controlled compared with self-implemented conditions on body weight and coronary artery disease (CAD) risk indicators in obese adults. DESIGN Sixteen obese subjects (12 women, 4 men) completed a 10-wk trial, which consisted of 3 phases: 1) a 2-wk control phase, 2) a 4-wk weight loss/ADF controlled food intake phase, and 3) a 4-wk weight loss/ADF self-selected food intake phase. RESULTS Dietary adherence remained high throughout the controlled food intake phase (days adherent: 86%) and the self-selected food intake phase (days adherent: 89%). The rate of weight loss remained constant during controlled food intake (0.67 +/- 0.1 kg/wk) and self-selected food intake phases (0.68 +/- 0.1 kg/wk). Body weight decreased (P < 0.001) by 5.6 +/- 1.0 kg (5.8 +/- 1.1%) after 8 wk of diet. Percentage body fat decreased (P < 0.01) from 45 +/- 2% to 42 +/- 2%. Total cholesterol, LDL cholesterol, and triacylglycerol concentrations decreased (P < 0.01) by 21 +/- 4%, 25 +/- 10%, and 32 +/- 6%, respectively, after 8 wk of ADF, whereas HDL cholesterol remained unchanged. Systolic blood pressure decreased (P < 0.05) from 124 +/- 5 to 116 +/- 3 mm Hg. CONCLUSION These findings suggest that ADF is a viable diet option to help obese individuals lose weight and decrease CAD risk. This trial was registered at clinicaltrials.gov as UIC-004-2009.

Degree of weight loss required to improve adipokine concentrations and decrease fat cell size in severely obese women

Adipose tissue physiology plays an important role in mediating disease risk. Weight loss in obese individuals improves indicators of adipocyte physiology. However, the minimum degree of weight loss required to elicit improvements remains unknown. The objective of the present study was to determine the minimum weight loss required to improve adipokine profile and decrease fat cell size in severely obese women. Thirteen severely obese women (body mass index, 50 +/- 3 kg/m(2); age, 35 +/- 1 years) consumed a low-calorie diet for 3 weeks with the goal of losing 5% of their initial weight. Subjects were divided into 2 weight loss groups posttreatment: less than 5% weight loss and 5% to 10% weight loss. Body weight was reduced (P < .05) in both groups (-1.4 +/- 1.0 and -6.8 +/- 0.6 kg, respectively). Adiponectin concentrations increased (P < .05) by 20% in the 5% to 10% weight loss group only. Likewise, leptin and resistin decreased (P < .05) by 37% and 27%, respectively, in the group that lost more weight. Visceral and subcutaneous fat cell size was 41% and 37% smaller (P < .01), respectively, in the 5% to 10% weight loss group. Smaller visceral adipocyte size was related to lower insulin (r = 0.82, P = .01) and glucose (r = 0.58, P = .04) concentrations posttreatment. These findings suggest that a minimum weight loss of 5% is required to improve adipokine profile and decrease fat cell size in severely obese women. These changes in adipocyte physiology may be linked to reductions in metabolic disease risk in this population.

Intermittent fasting combined with calorie restriction is effective for weight loss and cardio-protection in obese women

BackgroundIntermittent fasting (IF; severe restriction 1 d/week) facilitates weight loss and improves coronary heart disease (CHD) risk indicators. The degree to which weight loss can be enhanced if IF is combined with calorie restriction (CR) and liquid meals, remains unknown.ObjectiveThis study examined the effects of IF plus CR (with or without a liquid diet) on body weight, body composition, and CHD risk.MethodsObese women (n = 54) were randomized to either the IFCR-liquid (IFCR-L) or IFCR-food based (IFCR-F) diet. The trial had two phases: 1) 2-week weight maintenance period, and 2) 8-week weight loss period.ResultsBody weight decreased more (P = 0.04) in the IFCR-L group (3.9 ± 1.4 kg) versus the IFCR-F group (2.5 ± 0.6 kg). Fat mass decreased similarly (P < 0.0001) in the IFCR-L and IFCR-F groups (2.8 ± 1.2 kg and 1.9 ± 0.7 kg, respectively). Visceral fat was reduced (P < 0.001) by IFCR-L (0.7 ± 0.5 kg) and IFCR-F (0.3 ± 0.5 kg) diets. Reductions in total and LDL cholesterol levels were greater (P = 0.04) in the IFCR-L (19 ± 10%; 20 ± 9%, respectively) versus the IFCR-F group (8 ± 3%; 7 ± 4%, respectively). LDL peak particle size increased (P < 0.01), while heart rate, glucose, insulin, and homocysteine decreased (P < 0.05), in the IFCR-L group only.ConclusionThese findings suggest that IF combined with CR and liquid meals is an effective strategy to help obese women lose weight and lower CHD risk.

Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans

This study examined whether the combination of alternate day fasting (ADF) plus exercise produces superior changes in body composition and plasma lipid levels when compared to each intervention alone.

Comparison of effects of diet versus exercise weight loss regimens on LDL and HDL particle size in obese adults

BackgroundObesity is associated with an atherogenic lipid profile characterized by a predominance of small LDL and HDL particles. Weight loss, by dietary restriction or exercise, increases LDL particle size. Whether these interventions can augment HDL size in conjunction with LDL size remains unknown.ObjectiveThis study compared the effects of alternate day fasting (ADF), calorie restriction (CR), and endurance exercise on LDL and HDL particle size in overweight and obese subjects.MethodsIn a 12-week parallel-arm trial, adult subjects (n = 60) were randomized to 1 of 4 groups: 1) ADF (75% energy restriction for 24-h alternated with ad libitum feeding for 24-h), 2) CR (25% energy restriction every day), 3) exercise (moderate intensity training 3 x/week), or 4) control.ResultsBody weight was reduced (P < 0.001) by ADF, CR, and exercise (5.2 ± 1.1%, 5.0 ± 1.4%, 5.1 ± 0.9%, respectively). Plasma LDL cholesterol decreased (P < 0.05) with ADF (10 ± 4%) and CR (8 ± 4%), whereas HDL cholesterol increased (P < 0.05) with exercise (16 ± 5%). Integrated LDL particle size was augmented (P = 0.01) by ADF and CR. The proportion of small LDL particles decreased (P = 0.04) with ADF only, and the proportion of large HDL particles increased (P = 0.03) with exercise only.ConclusionThese results indicate that dietary restriction increases LDL particle size, while endurance training augments HDL particle size, with minimal weight loss. None of these interventions concomitantly increased both LDL and HDL particle size, however.

Dietary and physical activity adaptations to alternate day modified fasting: implications for optimal weight loss

BackgroundAlternate day modified fasting (ADMF) is an effective strategy for weight loss in obese adults.ObjectiveThe objective of this study was to examine the dietary and physical activity adaptations that occur during short-term ADMF, and to determine how these modulations affect rate of weight loss.MethodsSixteen obese subjects (12 women/4 men) completed a 10-week trial consisting of 3 phases: 1) 2-week control phase, 2) 4-week ADMF controlled feeding phase, and 3) 4-week ADMF self-selected feeding phase.ResultsBody weight decreased (P < 0.001) by 5.6 ± 1.0 kg post-treatment. Energy intake on the fast day was 26 ± 3% of baseline needs (501 ± 28 kcal/d). No hyperphagic response occurred on the feed day (95 ± 6% of baseline needs consumed, 1801 ± 226 kcal/d). Daily energy restriction (37 ± 7%) was correlated to rate of weight loss (r = 0.42, P = 0.01). Dietary fat intake decreased (36% to 33% of kcal, P < 0.05) with dietary counseling, and was related to rate of weight loss (r = 0.38, P = 0.03). Hunger on the fast day decreased (P < 0.05) by week 2, and remained low. Habitual physical activity was maintained throughout the study (fast day: 6416 ± 851 steps/d; feed day: 6569 ± 910 steps/d).ConclusionThese findings indicate that obese subjects quickly adapt to ADMF, and that changes in energy/macronutrient intake, hunger, and maintenance of physical activity play a role in influencing rate of weight loss by ADMF.

Improvement in coronary heart disease risk factors during an intermittent fasting/calorie restriction regimen: Relationship to adipokine modulations

BackgroundThe ability of an intermittent fasting (IF)-calorie restriction (CR) regimen (with or without liquid meals) to modulate adipokines in a way that is protective against coronary heart disease (CHD) has yet to be tested.ObjectiveAccordingly, we examined the effects of an IFCR diet on adipokine profile, body composition, and markers of CHD risk in obese women.MethodsSubjects (n = 54) were randomized to either the IFCR-liquid (IFCR-L) or IFCR-food based (IFCR-F) diet for 10 weeks.ResultsGreater decreases in body weight and waist circumference were noted in the IFCR-L group (4 ± 1 kg; 6 ± 1 cm) versus the IFCR-F group (3 ± 1 kg; 4 ± 1 cm). Similar reductions (P < 0.0001) in fat mass were demonstrated in the IFCR-L (3 ± 1 kg) and IFCR-F group (2 ± 1 kg). Reductions in total and LDL cholesterol levels were greater (P = 0.04) in the IFCR-L (19 ± 10%; 20 ± 9%, respectively) versus the IFCR-F group (8 ± 3%; 7 ± 4%, respectively). LDL peak particle size increased (P < 0.01) in the IFCR-L group only. The proportion of small LDL particles decreased (P < 0.01) in both groups. Adipokines, such as leptin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and insulin-like growth factor-1 (IGF-1) decreased (P < 0.05), in the IFCR-L group only.ConclusionThese findings suggest that IFCR with a liquid diet favorably modulates visceral fat and adipokines in a way that may confer protection against CHD.

Adipokine responses to acute resistance exercise in trained and untrained men.

INTRODUCTION Adipose tissue-derived hormones act as key mediators that may link active lifestyles to improved cardiovascular function. This study tested the hypothesis that a single weight training session would beneficially modulate adipokine profile in a way that would exert protection against endothelial dysfunction, in trained but not sedentary subjects. METHODS Male subjects (n = 43) were categorized into four separate groups based on exercise history: 1) sedentary, 2) weight trainers, 3) runners, or 4) weight trainer + runners. All subjects underwent a single progressive leg press weight training session (low weight for two sets of 8-12 repetitions each and then near-maximal exertion for three sets of 8-12 repetitions each). RESULTS There were no differences between groups for age, body weight, BMI, waist circumference, or percent body fat. Adiponectin increased (P < 0.05) by 30% and 37%, whereas resistin decreased (P < 0.05) by 35% and 34% in the weight trainers and weight trainer + runners, respectively, after training. Flow-mediated dilation (FMD) was impaired (P < 0.05) in sedentary subjects (-1.1 +/- 0.3%) but not in the athletic groups (1.7 +/- 0.4%). Improvements in FMD were associated with increased adiponectin (r = 0.61, P = 0.01), and decreased resistin (r = -0.56, P = 0.01) in weight trainers only. Leptin was not altered by acute resistance training in any group. There were no differences after training for total, LDL, HDL cholesterol, triglycerides, C-reactive protein levels, and systolic or diastolic blood pressure. Increased adiponectin was related to higher levels of HDL cholesterol after intervention (r = 0.71, P = 0.001). CONCLUSIONS These findings suggest that habitual resistance training may modulate adipokine profiles in a way that is protective against endothelial dysfunction.

Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial

Importance Alternate-day fasting has become increasingly popular, yet, to date, no long-term randomized clinical trials have evaluated its efficacy. Objective To compare the effects of alternate-day fasting vs daily calorie restriction on weight loss, weight maintenance, and risk indicators for cardiovascular disease. Design, Setting, and Participants A single-center randomized clinical trial of obese adults (18 to 64 years of age; mean body mass index, 34) was conducted between October 1, 2011, and January 15, 2015, at an academic institution in Chicago, Illinois. Interventions Participants were randomized to 1 of 3 groups for 1 year: alternate-day fasting (25% of energy needs on fast days; 125% of energy needs on alternating “feast days”), calorie restriction (75% of energy needs every day), or a no-intervention control. The trial involved a 6-month weight-loss phase followed by a 6-month weight-maintenance phase. Main Outcomes and Measures The primary outcome was change in body weight. Secondary outcomes were adherence to the dietary intervention and risk indicators for cardiovascular disease. Results Among the 100 participants (86 women and 14 men; mean [SD] age, 44 [11] years), the dropout rate was highest in the alternate-day fasting group (13 of 34 [38%]), vs the daily calorie restriction group (10 of 35 [29%]) and control group (8 of 31 [26%]). Mean weight loss was similar for participants in the alternate-day fasting group and those in the daily calorie restriction group at month 6 (–6.8% [95% CI, –9.1% to –4.5%] vs –6.8% [95% CI, –9.1% to –4.6%]) and month 12 (–6.0% [95% CI, –8.5% to –3.6%] vs –5.3% [95% CI, –7.6% to –3.0%]) relative to those in the control group. Participants in the alternate-day fasting group ate more than prescribed on fast days, and less than prescribed on feast days, while those in the daily calorie restriction group generally met their prescribed energy goals. There were no significant differences between the intervention groups in blood pressure, heart rate, triglycerides, fasting glucose, fasting insulin, insulin resistance, C-reactive protein, or homocysteine concentrations at month 6 or 12. Mean high-density lipoprotein cholesterol levels at month 6 significantly increased among the participants in the alternate-day fasting group (6.2 mg/dL [95% CI, 0.1-12.4 mg/dL]), but not at month 12 (1.0 mg/dL [95% CI, –5.9 to 7.8 mg/dL]), relative to those in the daily calorie restriction group. Mean low-density lipoprotein cholesterol levels were significantly elevated by month 12 among the participants in the alternate-day fasting group (11.5 mg/dL [95% CI, 1.9-21.1 mg/dL]) compared with those in the daily calorie restriction group. Conclusions and Relevance Alternate-day fasting did not produce superior adherence, weight loss, weight maintenance, or cardioprotection vs daily calorie restriction. Trial Registration clinicaltrials.gov Identifier: NCT00960505

Improvements in vascular health by a low-fat diet, but not a high-fat diet, are mediated by changes in adipocyte biology

BackgroundLow-fat (LF) and high-fat (HF) weight loss diets improve brachial artery flow-mediated dilation (FMD) in obese individuals, although results are conflicting. Moreover, the role that adipose tissue plays in mediating these diet-related effects are unknown.ObjectiveThis study examined how modulations in FMD by HF and LF diets relate to changes in adipocyte parameters.DesignObese subjects (n = 17) were randomized to a HF diet (60% kcal as fat) or a LF diet (25% kcal as fat) for 6 weeks. Both groups were restricted by 25% of energy needs.ResultsBody weight decreased (P < 0.05) in both groups (HF: -6.6 ± 0.5 kg, LF: -4.7 ± 0.6 kg). Fat mass and waist circumference were reduced (P < 0.05) in the LF group only (-4.4 ± 0.3 kg; -3.6 ± 0.8 cm, respectively). FMD improved (P < 0.05) in the LF group (7.4 ± 0.8% to 9.8 ± 0.8; 32% increase) and was impaired in the HF group (8.5 ± 0.6% to 6.9 ± 0.7; 19% reduction). Increases in plasma adiponectin (P < 0.05, 16 ± 5%), and decreases in resistin (P < 0.05, -26 ± 11%), were shown by the LF diet only. Greater decreases in leptin were observed with LF (-48 ± 9%) versus HF (-28 ± 12%) (P < 0.05, diet × time). Increased FMD by the LF diet was associated with increased adiponectin, and decreased fat mass, waist circumference, leptin, and resistin.ConclusionBeneficial modulations in vascular health by LF diets may be mediated by improvements in adipocyte parameters.