Protein leverage effects of beef protein on energy intake in humans.
BACKGROUND
The protein leverage hypothesis requires specific evidence that protein intake is regulated more strongly than energy intake.


OBJECTIVE
The objective was to determine ad libitum energy intake, body weight changes, appetite profile, and nitrogen balance in response to 3 diets with different protein-to-carbohydrate + fat ratios over 12 consecutive days, with beef as a source of protein.


METHODS
A 3-arm, 12-d randomized crossover study was performed in 30 men and 28 women [mean ± SD age: 33 ± 16 y; body mass index (in kg/m²): 24.4 ± 4.0] with the use of diets containing 5%, 15%, and 30% of energy (En%) from protein, predominantly from beef.


RESULTS
Energy intake was significantly lower in the 30En%-protein condition (8.73 ± 1.93 MJ/d) than in the 5En%-protein (9.48 ± 1.67 MJ/d) and 15En%-protein (9.30 ± 1.62 MJ/d) conditions (P = 0.001), stemming largely from lower energy intake during meals (P = 0.001). Hunger (P = 0.001) and desire to eat (P = 0.001) ratings were higher and fullness ratings were lower (P = 0.001) in the 5En%-protein condition than in the 15En%-protein and 30En%-protein conditions. Nitrogen excretion was lower in the 5En%-protein condition (4.7 ± 1.5 g/24 h; P = 0.001) and was higher in the 30En%-protein condition (15.3 ± 8.7 g/24 h; P = 0.001) compared with the 15En%-protein condition (10.0 ± 5.2 g/24 h). Nitrogen balance was maintained in the 5En%-protein condition and was positive in the 15En%- and 30En%-protein conditions (P = 0.001).


CONCLUSIONS
Complete protein leverage did not occur because subjects did not consume to a common protein amount at the expense of energy balance. Individuals did underconsume relative to energy requirements from high-protein diets. The lack of support for protein leverage effects on a low-protein diet may stem from the fact that protein intake was sufficient to maintain nitrogen balance over the 12-d trial.
From the Department of Human Biology, Maastricht University, Maastricht, Netherlands (EAM, MVD, and MSW-P), and the Department of Nutrition Science, Purdue University, West Lafayette, IN (S-YT and RDM).
Eveline A
EA
Martens
From the Department of Human Biology, Maastricht University, Maastricht, Netherlands (EAM, MVD, and MSW-P), and the Department of Nutrition Science, Purdue University, West Lafayette, IN (S-YT and RDM).
Sze-Yen
SY
Tan
From the Department of Human Biology, Maastricht University, Maastricht, Netherlands (EAM, MVD, and MSW-P), and the Department of Nutrition Science, Purdue University, West Lafayette, IN (S-YT and RDM).
Mandy V
MV
Dunlop
From the Department of Human Biology, Maastricht University, Maastricht, Netherlands (EAM, MVD, and MSW-P), and the Department of Nutrition Science, Purdue University, West Lafayette, IN (S-YT and RDM).
Richard D
RD
Mattes
From the Department of Human Biology, Maastricht University, Maastricht, Netherlands (EAM, MVD, and MSW-P), and the Department of Nutrition Science, Purdue University, West Lafayette, IN (S-YT and RDM).
Margriet S
MS
Westerterp-Plantenga
D000293:Adolescent; D000328:Adult; D000818:Animals; D001069:Appetite Regulation; D015415:Biomarkers / Q000652:urine; D002417:Cattle; D018592:Cross-Over Studies; D018753:Diet, Protein-Restricted / Q000009:adverse effects; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D008460:Meat / Q000009:adverse effects; D008875:Middle Aged; D009124:Muscle Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D009584:Nitrogen / Q000652:urine; D016037:Single-Blind Method; D015431:Weight Loss; D055815:Young Adult
D015415:Biomarkers; D004044:Dietary Proteins; D009124:Muscle Proteins; D009584:Nitrogen