Obesity Journal Club

Obesity Journal Club 12/4/18 at 12pm in M&V 240

The Obesity Journal Club will meet on Tuesday, December 4th from 12-1pm in M&V 240 and via WebEx (see details below).

This is the last OJC meeting of 2018, we hope to see you all there!
In the spirit of the article, we will be serving high-fat imported cheeses, but we will ration the crackers.

Presenter: Misha Eliasziw, Ph.D.
Article Title: Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial
Authors/Journal: Ebbeling et al. (2018) in British Medical Journal
DOI: http://dx.doi.org/10.1136/bmj.k4583

Article Abstract

Objective: To determine the effects of diets varying in carbohydrate to fat ratio on total energy expenditure.

Design: Randomized trial.

Setting: Multicenter collaboration at US two sites, August 2014 to May 2017.

Participants: 164 adults aged 18-65 years with a body mass index of 25 or more.

Interventions: After 12% (within 2%) weight loss on a run-in diet, participants were randomly assigned to one ofthree test diets according to carbohydrate content (high, 60%, n=54; moderate, 40%, n=53; or low, 20%, n=57) for 20 weeks. Test diets were controlled for protein and were energy adjusted to maintain weight loss within 2 kg. To test for effect modification predicted by the carbohydrate-insulin model, the sample was divided into thirds of pre-weight loss insulin secretion (insulin concentration 30 minutes after oral glucose).

Main outcome measures: The primary outcome was total energy expenditure, measured with doubly labeled water, by intention- to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate. Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.

Results: Total energy expenditure differed by diet in the intention-to-treat analysis (n=162, P=0.002), with a linear trend of 52 kcal/d (95% confidence interval 23 to 82) for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ). Change in total energy expenditure was 91 kcal/d (95% confidence interval −29 to 210) greater in participants assigned to the moderate carbohydrate diet and 209 kcal/d (91 to 326) greater in those assigned to the low carbohydrate diet compared with the high carbohydrate diet. In the per protocol analysis (n=120, P<0.001), the respective differences were 131 kcal/d (−6 to 267) and 278 kcal/d (144 to 411). Among participants in the highest third of pre-weight loss insulin secretion, the difference between the low and high carbohydrate diet was 308 kcal/d in the intention-to-treat analysis and 478 kcal/d in the per protocol analysis (P<0.004). Ghrelin was significantly lower in participants assigned to the low carbohydrate diet comparedwith those assigned to the high carbohydrate diet (both analyses). Leptin was also significantly lower in participants assigned to the low carbohydrate diet (per protocol).

Conclusions: Consistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance. This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion.

Trial registration: ClinicalTrials.gov NCT02068885.

WebEx Information
Meeting link: https://tufts.webex.com/tufts/j.php?MTID=m86c55d4042b3b5880a941c8f483d4c11
Audio connection: +1-617-627-6767
Meeting number (access code): 736 392 434
Meeting password: vFUEM243

The Obesity Journal Club is a program of the Boston Nutrition Obesity Research Center’s (BNORC). Aviva Must serves as the faculty facilitator. The general format includes the presentation, critique, and (we hope) thoughtful discussion of a current article from the peer-reviewed obesity literature. Faculty and students in the greater Boston area are welcome to attend and present. It is also possible to connect by WebEx and participate virtually—upon request.

Announcements for each meeting will come ~1 week in advance and will specify the paper we will review and critique. For those at Tufts, light snacks are served but please bring your own beverage. Obesity Journal Club will meet from 12-1pm on the 1st and 3rd Tuesday of every month from September to May.

Obesity Journal Club is participatory. We will ask for student and faculty volunteers to sign up and present an article of their choice at future meetings. Assistance in selecting an article for presentation is available. This is a great opportunity for students to develop presentation skills in a friendly low-risk environment. Sign up for the Fall meetings will take place at our first meeting on September 18th.

If you wish to be added to (or removed from) the Obesity Journal Club listserv, please email Ariella.Korn@tufts.edu or Katherine.Rancano@tufts.edu.