Carbohydrate for weight and metabolic control: where do we stand?
ABSTRACT Changes in lifestyle are considered to play an important role in the etiology of obesity and type 2 diabetes, and improvements in diet and physical activity are the first-choice treatment for these metabolic diseases. Since the dietary recommendations of almost 40 y ago that fat should be decreased and that carbohydrate should be increased, recommendations for a healthy diet, except for minor amendments, have not changed that much. It is generally considered that caloric restriction is more important than changes in the macronutrient composition of the diet for weight loss and body weight control. Although this is true, there is increasing evidence that changes in the macronutrient composition of the diet (decreasing carbohydrate and increasing unsaturated fats and/or protein) play a role that facilitates weight loss, increases insulin sensitivity and glucose tolerance, and improves cardiovascular risk factors, such as blood pressure, blood lipid profile, and inflammatory markers, often independent of weight loss. Low-carbohydrate diets, whether they be high in unsaturated fats and/or protein, are not recommended by the American Diabetes Association; however, despite this the Joslin Diabetes Center currently advocates a diet composition of approximately 40% carbohydrate, 30% fat, and 30% protein energy for overweight and obese adults with type 2 diabetes or prediabetes or those at high risk of developing type 2 diabetes. Hopefully, future studies will indicate whether diets with a more equilibrated macronutrient composition than presently recommended are more appropriate for body weight and metabolic control.
Article: Protein leverage and energy intake.[Show abstract] [Hide abstract]
ABSTRACT: Increased energy intakes are contributing to overweight and obesity. Growing evidence supports the role of protein appetite in driving excess intake when dietary protein is diluted (the protein leverage hypothesis). Understanding the interactions between dietary macronutrient balance and nutrient-specific appetite systems will be required for designing dietary interventions that work with, rather than against, basic regulatory physiology. Data were collected from 38 published experimental trials measuring ad libitum intake in subjects confined to menus differing in macronutrient composition. Collectively, these trials encompassed considerable variation in percent protein (spanning 8-54% of total energy), carbohydrate (1.6-72%) and fat (11-66%). The data provide an opportunity to describe the individual and interactive effects of dietary protein, carbohydrate and fat on the control of total energy intake. Percent dietary protein was negatively associated with total energy intake (F = 6.9, P < 0.0001) irrespective of whether carbohydrate (F = 0, P = 0.7) or fat (F = 0, P = 0.5) were the diluents of protein. The analysis strongly supports a role for protein leverage in lean, overweight and obese humans. A better appreciation of the targets and regulatory priorities for protein, carbohydrate and fat intake will inform the design of effective and health-promoting weight loss diets, food labelling policies, food production systems and regulatory frameworks.Obesity Reviews 03/2014; 15(3):183-91. DOI:10.1111/obr.12131 · 7.86 Impact Factor
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ABSTRACT: Diets to decrease body weight have limited success in achieving and importantly maintaining this weight loss long-term. It has recently been suggested that energy intake can be regulated by the amount of protein ingested, termed the protein leverage hypothesis. In this study, we determined whether a high protein diet would be effective in achieving and maintaining weight loss in a genetically obese model, the New Zealand Obese (NZO) mouse. NZO and C57BL/6J (C57) control mice were fed a high protein or chow diet for 5 weeks from weaning (3 weeks of age). Body weight and food intake were determined. Mice on the same diet were bred to produce offspring that were fed either a chow or high protein diet. Body weight, food intake, and glucose tolerance were determined. Feeding NZO and C57 mice a high protein diet for 5 weeks resulted in reduced food intake and consequently energy intake and body weight gain compared with mice on a chow diet. NZO mice fed a high protein diet showed a significant improvement in glucose tolerance compared with their chow-fed counterparts, while no difference was seen in C57 mice fed chow or protein diet. The offspring of NZO mice that were fed a high protein diet during gestation and weaning were also lighter and displayed improved glucose tolerance compared with chow fed animals. We conclude that a high protein diet is a reasonable strategy to reduce body weight gain and improve glucose tolerance in the NZO mouse, a polygenic model of obesity.Hormone and Metabolic Research 10/2014; DOI:10.1055/s-0034-1389991 · 2.04 Impact Factor
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ABSTRACT: OBJECTIVE To test whether a weight loss program promotes greater weight loss, glycemic control, and improved cardiovascular disease risk factors compared with control conditions and whether there is a differential response to higher versus lower carbohydrate intake.RESEARCH DESIGN AND METHODS This randomized controlled trial at two university medical centers enrolled 227 overweight or obese adults with type 2 diabetes and assigned them to parallel in-person diet and exercise counseling, with prepackaged foods in a planned menu during the initial phase, or to usual care (UC; two weight loss counseling sessions and monthly contacts).RESULTSRelative weight loss was 7.4% (95% CI, 5.7-9.2%), 9.0% (7.1-10.9%), and 2.5% (1.3-3.8%) for the lower fat, lower carbohydrate, and UC groups (P < 0.001 intervention effect). Glycemic control markers and triglyceride levels were lower in the intervention groups compared with UC group at 1 year (fasting glucose 141 [95% CI, 133-149] vs. 159 [144-174] mg/dL, P = 0.010; hemoglobin A1c 6.9% [6.6-7.1%] vs. 7.5% [7.1-7.9%] or 52 [49-54] vs. 58 [54-63] mmol/mol, P = 0.001; triglycerides 148 [134-163] vs. 204 [173-234] mg/dL, P < 0.001). The lower versus higher carbohydrate groups maintained lower hemoglobin A1c (6.6% [95% CI, 6.3-6.8%] vs. 7.2% [6.8-7.5%] or 49 [45-51] vs. 55 [51-58] mmol/mol) at 1 year (P = 0.008).CONCLUSIONS The weight loss program resulted in greater weight loss and improved glycemic control in type 2 diabetes.Diabetes care 04/2014; 37(6). DOI:10.2337/dc13-2900 · 8.57 Impact Factor