A Randomized Trial Comparing Low‐Fat and Low‐Carbohydrate Diets Matched for Energy and Protein

Abstract

Several recent studies have found greater weight loss at 6 months among participants on a very-low-carbohydrate (VLC) weight-loss diet compared with a low-fat (LF) weight-loss diet. Because most of these studies were not matched for calories, it is not clear whether these results are caused by decreased energy intake or increased energy expenditure. It is hypothesized that several energy-consuming metabolic pathways are up-regulated during a VLC diet, leading to increased energy expenditure. The focus of this study was to investigate whether, when protein and energy are held constant, there is a significant difference in fat and weight loss when fat and carbohydrate are dramatically varied in the diet. The preliminary results presented in this paper are for the first four of six postmenopausal overweight or obese participants who followed, in random order, both a VLC and an LF diet for 6 weeks. Other outcome measures were serum lipids, glucose, and insulin, as well as dietary compliance and side effects. Our results showed no significant weight loss, lipid, serum insulin, or glucose differences between the two diets. Lipids were dramatically reduced on both diets, with a trend for greater triglyceride reduction on the VLC diet. Glucose levels were also reduced on both diets, with a trend for insulin reduction on the VLC diet. Compliance was excellent with both diets, and side effects were mild, although participants reported more food cravings and bad breath on the VLC diet and more burping and flatulence on the LF diet.

Protein Intake during Energy Restriction: Effects on Body Composition and Markers of Metabolic and Cardiovascular Health in Postmenopausal Women

“…Results from previous shorter-term studies reported neither MHP or HP [9][10][11][13][14][15][16][17][18][19] diets achieved greater reductions in body mass, FM or FFM when compared to lower protein diets. This supports our results with the BEEF group compared to CARB.…”

“…Most MHP/HP ER studies have not observed a diet effect on total and LDL cholesterol concentrations [1,[3][4][5][6]9,11,[16][17][18][19][20][21]. However, mixed results have been reported for the influence of MHP on triacylglycerol with studies showing greater improvement [1][2][3][4][5][6]11,16,[18][19][20][22][23][24], or no difference [1,6,16,17,19,21,25] compared to LP diets. Our results for lower total and LDL cholesterol concentrations as well as no change in triacylglycerol concentration (although a trend was observed, Table 4) are similar to findings in a study [29] that compared two 1250 kcal MHP diets (both 20% protein, beef vs. chicken) in pre-menopausal women.…”

“…Enhanced body mass loss and favorable body composition changes attributed to MHP/HP intake may be due to increased satiety [5,9], thermic effect of food [12], and/or resting energy expenditure [6]. In contrast, other shorter-term [9][10][11][13][14][15][16][17][18][19] and longer-term (1 year) [2,20,21] studies indicate that MHP/ HP intakes did not enhance body mass loss or affect body composition changes compared to LP diets.…”

Macronutrients and type 1 diabetes (revision number 6)

“…Four randomised controlled trials were identified that presented evidence on diets differing in the proportion of carbohydrate to fat or protein in relation to blood glucose response two hours after an oral glucose tolerance test (Swinburn et al, 2001;Lasker et al, 2008;Due et al, 2008a). No further trials were identified in the update search (Cardio-metabolic review, diabetes chapter p185) (Racette et al, 1995;Golay et al, 1996;Golay et al, 2000;Swinburn et al, 2001;Helge, 2002;Colette et al, 2003;Landry et al, 2003;Lovejoy et al, 2003;Wolever & Mehling, 2003;Clifton et al, 2004;Segal-Isaacson et al, 2004;Dansinger et al, 2005;Lofgren et al, 2005;Raatz et al, 2005;Petersen et al, 2006;Howard et al, 2006b;Ebbeling et al, 2007;Gardner et al, 2007;Maki et al, 2007b;Phillips et al, 2008;Due et al, 2008a;Frisch et al, 2009;Grau et al, 2009;Kirk et al, 2009;Morgan et al, 2009;Sacks et al, 2009). Five trials were subsequently identified in the update search (Goree et al, 2011;Haufe et al, 2011;Shikany et al, 2011;Tierney et al, 2011;Brooking et al, 2012 Nearly all trials employ energy restricted weight loss diets that vary both carbohydrate (between 5% and 65% energy) and fat (between 18% and 40% energy) between groups.…”

“…a concomitant reduction in saturated fat intake and/or weight loss  The effect is biologically relevant Fasting HDL-cholesterol 5.36. Twenty two randomised controlled trials that presented evidence on diets differing in the proportion of carbohydrate to fat on fasting HDL-cholesterol were included in the metaanalysis (Campos et al, 1995;Nelson et al, 1995;Ginsberg et al, 1998;Turley et al, 1998;Zambon et al, 1999;Golay et al, 2000;Wolever & Mehling, 2002;Foster et al, 2003;Colette et al, 2003;Couture et al, 2003;Lovejoy et al, 2003;Clifton et al, 2004;Ley et al, 2004;Pelkman et al, 2004;Segal-Isaacson et al, 2004;Cornier et al, 2005;Bhargava, 2006;Petersen et al, 2006;Howard et al, 2006b;Ebbeling et al, 2007;Due et al, 2008b;Frisch et al, 2009). Seven trials were subsequently identified in the update search Howard et al, 2010;Foster et al, 2010;Haufe et al, 2011;Tierney et al, 2011;de Souza et al, 2012;Brooking et al, 2012) Of the trials identified in the update search, four report no significant effect of diets differing in the proportion of carbohydrate and fat on fasting HDL-cholesterol concentration (Howard et al, 2010;Haufe et al, 2011;de Souza et al, 2012;Brooking et al, 2012).…”