1.
Effect of a Personalized Diet to Reduce Postprandial Glycemic Response vs a Low-fat Diet on Weight Loss in Adults With Abnormal Glucose Metabolism and Obesity: A Randomized Clinical Trial.
Popp, CJ, Hu, L, Kharmats, AY, Curran, M, Berube, L, Wang, C, Pompeii, ML, Illiano, P, St-Jules, DE, Mottern, M, et al
JAMA network open. 2022;5(9):e2233760
-
-
-
Free full text
-
Plain language summary
Postprandial glycaemic response (PPGR) to foods can be different from person to person. This could be the reason why people experience different weight loss outcomes with standardised diets such as a low glycaemic index diet, low-fat diet or a low carbohydrate diet. In this single-centre, population-based, randomised, blinded clinical trial, 204 participants with irregular glucose metabolism and obesity were randomised to consume either a low-fat or personalised diet for six months in combination with fourteen behavioural change counselling sessions. The participants in the personalised diet group received a colour-coded meal score to indicate their estimated PPGR for different foods. The results of this study showed no significant weight reduction in the personalised diet group compared to the low-fat diet. Further robust studies are required to develop appropriate precision nutrition interventions for weight loss and energy balance. However, healthcare professionals can use the results of this study to understand that both a low-fat diet and a personalised diet, coupled with behavioural counselling, may be effective in promoting weight loss in obese populations with irregular glucose metabolism.
Abstract
IMPORTANCE Interindividual variability in postprandial glycemic response (PPGR) to the same foods may explain why low glycemic index or load and low-carbohydrate diet interventions have mixed weight loss outcomes. A precision nutrition approach that estimates personalized PPGR to specific foods may be more efficacious for weight loss. OBJECTIVE To compare a standardized low-fat vs a personalized diet regarding percentage of weight loss in adults with abnormal glucose metabolism and obesity. DESIGN, SETTING, AND PARTICIPANTS The Personal Diet Study was a single-center, population-based, 6-month randomized clinical trial with measurements at baseline (0 months) and 3 and 6 months conducted from February 12, 2018, to October 28, 2021. A total of 269 adults aged 18 to 80 years with a body mass index (calculated as weight in kilograms divided by height in meters squared) ranging from 27 to 50 and a hemoglobin A1c level ranging from 5.7% to 8.0% were recruited. Individuals were excluded if receiving medications other than metformin or with evidence of kidney disease, assessed as an estimated glomerular filtration rate of less than 60 mL/min/1.73 m2 using the Chronic Kidney Disease Epidemiology Collaboration equation, to avoid recruiting patients with advanced type 2 diabetes. INTERVENTIONS Participants were randomized to either a low-fat diet (<25% of energy intake; standardized group) or a personalized diet that estimates PPGR to foods using a machine learning algorithm (personalized group). Participants in both groups received a total of 14 behavioral counseling sessions and self-monitored dietary intake. In addition, the participants in the personalized group received color-coded meal scores on estimated PPGR delivered via a mobile app. MAIN OUTCOMES AND MEASURES The primary outcome was the percentage of weight loss from baseline to 6 months. Secondary outcomes included changes in body composition (fat mass, fat-free mass, and percentage of body weight), resting energy expenditure, and adaptive thermogenesis. Data were collected at baseline and 3 and 6 months. Analysis was based on intention to treat using linear mixed modeling. RESULTS Of a total of 204 adults randomized, 199 (102 in the personalized group vs 97 in the standardized group) contributed data (mean [SD] age, 58 [11] years; 133 women [66.8%]; mean [SD] body mass index, 33.9 [4.8]). Weight change at 6 months was -4.31% (95% CI, -5.37% to -3.24%) for the standardized group and -3.26% (95% CI, -4.25% to -2.26%) for the personalized group, which was not significantly different (difference between groups, 1.05% [95% CI, -0.40% to 2.50%]; P = .16). There were no between-group differences in body composition and adaptive thermogenesis; however, the change in resting energy expenditure was significantly greater in the standardized group from 0 to 6 months (difference between groups, 92.3 [95% CI, 0.9-183.8] kcal/d; P = .05). CONCLUSIONS AND RELEVANCE A personalized diet targeting a reduction in PPGR did not result in greater weight loss compared with a low-fat diet at 6 months. Future studies should assess methods of increasing dietary self-monitoring adherence and intervention exposure. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03336411.
2.
Calorie restriction improves metabolic state independently of gut microbiome composition: a randomized dietary intervention trial.
Sowah, SA, Milanese, A, Schübel, R, Wirbel, J, Kartal, E, Johnson, TS, Hirche, F, Grafetstätter, M, Nonnenmacher, T, Kirsten, R, et al
Genome medicine. 2022;14(1):30
-
-
-
Free full text
Plain language summary
Obesity is an important risk factor for chronic diseases. Aside from well-established mechanisms such as obesity-induced inflammation, alterations in sugar and lipid metabolism, and steroid hormone signalling, imbalances in the composition of the gut microbiome have also been linked to the progression of obesity and its cardio-metabolic sequelae. The aim of this study was to investigate whether intermittent calorie restriction (ICR) (operationalised as the 5:2 diet) or continuous calorie restriction (CCR) induced alterations in the gut microbiome, and to which extent these were associated with overall weight loss irrespective of the dietary intervention in overweight or obese adults. This study was conducted using data and samples of the HELENA trial which was a parallel-arm randomised controlled trial. Participants were randomly assigned to one of three groups, i.e., an ICR (n = 49), a CCR (n = 49), or a control group (n = 52) over a 50-week period in a 1:1:1 ratio. Results showed that the type of calorie restriction or the amount of weight lost were not accompanied by substantial and consistent shifts in gut microbiome composition or the abundance of individual bacterial taxa. Authors conclude that moderate ICR or CCR interventions as well as an overall moderate weight loss induced by calorie restriction (irrespective of which form) may not be associated with significant changes in the gut microbiome of overweight and obese adults, notwithstanding observed metabolic improvements.
Abstract
BACKGROUND The gut microbiota has been suggested to play a significant role in the development of overweight and obesity. However, the effects of calorie restriction on gut microbiota of overweight and obese adults, especially over longer durations, are largely unexplored. METHODS Here, we longitudinally analyzed the effects of intermittent calorie restriction (ICR) operationalized as the 5:2 diet versus continuous calorie restriction (CCR) on fecal microbiota of 147 overweight or obese adults in a 50-week parallel-arm randomized controlled trial, the HELENA Trial. The primary outcome of the trial was the differential effects of ICR versus CCR on gene expression in subcutaneous adipose tissue. Changes in the gut microbiome, which are the focus of this publication, were defined as exploratory endpoint of the trial. The trial comprised a 12-week intervention period, a 12-week maintenance period, and a final follow-up period of 26 weeks. RESULTS Both diets resulted in ~5% weight loss. However, except for Lactobacillales being enriched after ICR, post-intervention microbiome composition did not significantly differ between groups. Overall weight loss was associated with significant metabolic improvements, but not with changes in the gut microbiome. Nonetheless, the abundance of the Dorea genus at baseline was moderately predictive of subsequent weight loss (AUROC of 0.74 for distinguishing the highest versus lowest weight loss quartiles). Despite the lack of consistent intervention effects on microbiome composition, significant study group-independent co-variation between gut bacterial families and metabolic biomarkers, anthropometric measures, and dietary composition was detectable. Our analysis in particular revealed associations between insulin sensitivity (HOMA-IR) and Akkermansiaceae, Christensenellaceae, and Tanerellaceae. It also suggests the possibility of a beneficial modulation of the latter two intestinal taxa by a diet high in vegetables and fiber, and low in processed meat. CONCLUSIONS Overall, our results suggest that the gut microbiome remains stable and highly individual-specific under dietary calorie restriction. TRIAL REGISTRATION The trial, including the present microbiome component, was prospectively registered at ClinicalTrials.gov NCT02449148 on May 20, 2015.