Long-term effects of a high-protein weight-loss diet.
BACKGROUND
Evidence that high-protein diets are an effective strategy for the maintenance of long-term weight loss is limited.


OBJECTIVE
The objective was to determine the efficacy of a higher protein intake on the maintenance of weight loss after 64 wk of follow-up.


METHODS
Seventy-nine healthy women with a mean (+/-SD) age of 49+/-9 y and a body mass index (in kg/m2) of 32.8+/-3.5 completed an intensive 12-wk weight-loss program and 52 wk of follow-up to compare the effects on weight-loss maintenance of a high-protein (HP) diet (34% of energy) or a high-carbohydrate (HC) diet (64% of energy).


RESULTS
Mean (+/-SD) weight loss was not significantly different between groups: (HP: 4.6+/-5.5 kg; HC: 4.4+/-6.1 kg). Protein intake (g) from dietary records at 64 wk was directly related to weight loss (P<0.0001), accounting for 15% of the variance. Protein intake as a percentage of energy was also related to weight change (P=0.003), accounting for 10% of the variance. In the upper tertile (88 g protein/d), weight loss was 6.5+/-7.5 and 3.4+/-4.4 kg (P=0.03) in the 2 lower tertiles, respectively. This difference did not translate to a difference in central fat loss between groups. Lipids, glucose, insulin, C-reactive protein, and homocysteine all improved with weight loss and were not significantly different between groups. HDL cholesterol rose by 20%. Higher serum vitamin B-12 was observed in the HP group, and folate concentrations were not significantly different between groups.


CONCLUSIONS
A reported higher protein intake appears to confer some weight-loss benefit. Cardiovascular disease risk factors, biomarkers of disease, and serum vitamins and minerals improved with no differences between groups.
Clifton
Peter M
PM
CSIRO Human Nutrition, Adelaide, Australia. peter.clifton@csiro.au
Keogh
Jennifer B
JB
Noakes
Manny
M
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002097:C-Reactive Protein / Q000378:metabolism; D050528:Diet, Carbohydrate-Restricted; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy*; D013997:Time Factors; D016896:Treatment Outcome; D016482:Urinalysis; D015431:Weight Loss
D015415:Biomarkers; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D007328:Insulin; D008055:Lipids; D002097:C-Reactive Protein