A randomized trial of a hypocaloric high-protein diet, with and without exercise, on weight loss, fitness, and markers of the Metabolic Syndrome in overweight and obese women

Abstract

The purpose of this study was to examine the effects of 3:1 and 1:1 carbohydrate to protein ratios, hypocaloric diets with and without exercise, and risk factors associated with the Metabolic Syndrome in overweight and obese Canadian women. Groups were designated as control diet (CON), control diet with exercise (CONEx), high-protein (HP), or high-protein with exercise (HPEx). Free-living women from the Guelph community were studied in a university health and fitness facility. The participants were 44 of 60 overweight and obese women who had been randomized to the 4 weight-loss programs. Habitual diets of the subjects were energy restricted and were to contain either a 1:1 or 3:1 ratio of carbohydrate to protein energy. Subjects either exercised 3 times/week or maintained their normal level of activity for 12 weeks. The main outcome measures were weight loss, blood lipids, blood pressure, insulin, body composition, nitrogen balance, fitness, and resting energy expenditure. All groups lost weight over the 12 week period: -2.1 kg for the CON group, -4.0 kg in the CONEx group, -4.6 kg in the HP group, and -7.0 kg in the HPEx. All participants exhibited improved body composition, decreased blood pressure, and decreased waist and hip circumference. Actual diets consumed by the subjects contained ratios of carbohydrate to protein of 3.0:1, 2.7:1, 1.5:1, and 0.96:1 for the CON, CONEx, HP, and HPEx groups, respectively. Cardiovascular fitness improved in both exercise groups. There were no changes in resting energy expenditure. No adverse events were reported. Significant changes in blood lipids included decreased total cholesterol in the HP and CONEx groups, decreased low-density lipoprotein cholesterol in the HP group only, and decreased blood triglycerides in the HPEx group only. High-density lipoprotein cholesterol, fasting blood glucose, and fasting insulin levels were unaltered by diet or exercise. A high-protein diet was superior to a low-fat, high-carbohydrate diet either alone or when combined with an aerobic/resistance-training program in promoting weight loss and nitrogen balance, while similarly improving body composition and risk factors for the Metabolic Syndrome in overweight and obese Canadian women.

Personalized weight loss strategies—the role of macronutrient distribution

“…Diets rich in protein and low glycaemic index carbohydrates also improve satiety and avoid or reduce excess weight gain 39,48,119 . Animal and human studies also show that fat intake is potentially linked to overeating and a positive energy balance 44,120 , although high fat diets do not necessarily cause weight gain 52,53 , and lowcarbohydrate diets (high-protein or high fat) have shown to be as effective as control or low-fat diets in weight loss treatments 35,37,40,54,68 Furthermore, the advances in bioinformatics and 'omics' technologies may herald a new era in personalized medicine, 121 although applications of epigenetic and genome-wide profiling are some way from clinical implementation or global consensus.…”

“…In one study, 68 44 overweight or obese women were assigned to one of two energy-restricted dietary programs (carbohydrate:protein ratios of either 3:1 or 1:1), with or without regular exercise. 68 After 12 weeks, women in the high-protein diet plus exercise group had lost an average of 7 kg, whereas the control (standard-protein diet, no exercise) group achieved an average weight loss of 2.1 kg. The high-protein, no-exercise group also achieved an average weight loss of 4.6 kg.…”

Macronutrients and type 1 diabetes (revision number 6)

“…Two trials were subsequently identified in the update search (Toscani et al, 2011;Gogebakan et al, 2011) Fasting total cholesterol 5.50. Twenty three randomised controlled trials that presented evidence on diets differing in the proportion of carbohydrate to protein and fat on fasting total cholesterol were included in the meta-analysis (Clevidence et al, 1992;Golay et al, 1996;Brehm et al, 2003;Johnston et al, 2004;Meckling et al, 2004;Brehm et al, 2005;Dansinger et al, 2005;Ebbeling et al, 2005;Layman et al, 2005;Krauss et al, 2006;McMillan-Price et al, 2006;Noakes et al, 2006;Keogh et al, 2007;Mahon et al, 2007;Meckling & Sherfey, 2007;Maki et al, 2007b;Keogh et al, 2008;Lasker et al, 2008;Phillips et al, 2008;Stoernell et al, 2008;Sacks et al, 2009;de Luis et al, 2009b). Five trials were subsequently identified in the update search (Al-Sarraj et al, 2010;Krebs et al, 2010;Klemsdal et al, 2010;Lim et al, 2010;Wycherley et al, 2010) (Cardiometabolic review, the hyperlipidaemias and blood lipids chapter p 70-71; Update search table 72).…”

“…Seven randomised controlled trials were identified that presented evidence on diets differing in the proportion of carbohydrate to protein and fat on systolic and diastolic blood pressure, all of which were included in the meta-analysis (Brehm et al, 2003;Meckling et al, 2004;Brehm et al, 2005;Keogh et al, 2007;Meckling & Sherfey, 2007;Keogh et al, 2008;de Luis et al, 2009b). Three trials were subsequently identified in the update search (Klemsdal et al, 2010;Lim et al, 2010;Wood et al, 2012) (Cardiometabolic review, incident hypertension and blood pressure chapter p 52, 56; Update search table 49).…”

Modulating Weight Loss and Regain through Exercise and Dietary Protein

“…Finally, a series of studies investigating the carbohydrate to protein ratio of diets as a determinant of weight loss showed ratios (1.0-1.4) corresponding to 1.0-1.6 g/kg protein produced more weight loss than ratios (3.0-3.5) corresponding to 0.7-0.8 g/ kg protein with 20, 21 or without 39 exercise in short-term interventions. However, many studies failed to find significant differences in weight loss between low-and high-protein diets.…”