High-protein, low-fat diets are effective for weight loss and favorably alter biomarkers in healthy adults.
Although popular and effective for weight loss, low-carbohydrate, high-protein, high-fat (Atkins) diets have been associated with adverse changes in blood and renal biomarkers. High-protein diets low in fat may represent an equally appealing diet plan but promote a more healthful weight loss. Healthy adults (n = 20) were randomly assigned to 1 of 2 low-fat (<30% energy), energy-restricted groups: high-protein (30% energy) or high-carbohydrate (60% energy); 24-h intakes were strictly controlled during the 6-wk trial. One subject from each group did not complete the trial due to out-of-state travel; two subjects in the high-carbohydrate group withdrew from the trial due to extreme hunger. Body composition and metabolic indices were assessed pre- and post-trial. Both diets were equally effective at reducing body weight (-6%, P < 0.05) and fat mass (-9 to -11%, P < 0.05); however, subjects consuming the high-protein diet reported more satisfaction and less hunger in mo 1 of the trial. Both diets significantly lowered total cholesterol (-10 to -12%), insulin (-25%), and uric acid (-22 to -30%) concentrations in blood from fasting subjects. Urinary calcium excretion increased 42% in subjects consuming the high-protein diet, mirroring the 50% increase in dietary calcium with consumption of this diet; thus, apparent calcium balance was not adversely affected. Creatinine clearance was not altered by diet treatments, and nitrogen balance was more positive in subjects consuming the high-protein diet vs. the high-carbohydrate diet (3.9 +/- 1.4 and 0.7 +/- 1.7 g N/d, respectively, P < 0.05). Thus, low-fat, energy-restricted diets of varying protein content (15 or 30% energy) promoted healthful weight loss, but diet satisfaction was greater in those consuming the high-protein diet.
Department of Nutrition, Arizona State University, Mesa, AZ 85212, USA. carol.johnston@asu.edu
Carol S
CS
Johnston
Sherrie L
SL
Tjonn
Pamela D
PD
Swan
D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001823:Body Composition; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D018752:Diet, Fat-Restricted; D004044:Dietary Proteins; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D012527:Satiation; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*
D015415:Biomarkers; D004044:Dietary Proteins; D002784:Cholesterol