Purdue University Weight Loss Study

• A reduced-calorie diet with a higher amount of protein helped overweight women retain more lean body mass while losing weight compared to women who consumed the same amount of calories but ate less protein.
   
• On average, the women in the higher protein group consumed about 6 ounces of lean pork per day in a diet of approximately 30% of calories from protein.
   
• The women in the study who increased their dietary protein, with pork as the only source of meat, reported feeling fuller after a meal and rated themselves more positively in terms of overall mood and feelings of pleasure during dieting.
   
• The preservation of lean body mass was more pronounced in the pre-obese women compared with the obese women. The pre-obese group lost 2.6 pounds of lean body mass compared to 6.4 pounds of lean body mass lost by the obese women.
   
• Normal indicators of kidney function and cardiovascular health were comparable between both groups, and blood pressure and lipid-lipoprotein profile (cholesterol and triglycerides) improved with weight loss.

Researchers: Scientists at Purdue University.

Sponsor: The study was funded by the National Pork Board.

Methodology: To determine the effect of higher protein intake from lean sources of pork, on weight loss and satiety, 46 overweight or obese women were assigned to one of two different low-calorie diets: a high protein diet (30% of total calories) that included about six ounces of lean pork products, or normal protein diet (18% of total calories) that did not include any meats. Both groups of dieters consumed the same amount of calories – 750 fewer calories than their normal daily intake – and percent of calories from fat (25% of total calories) for 12 weeks.

Analysis: The researchers tracked the participants’ food intake, body weight and composition, plus their feelings of fullness and satisfaction throughout the study to compare the effect of the two different diets.

Conclusions: While all of the women lost about 18 pounds over the course of the study, the researchers found that a reduced-calorie diet with a higher protein content – about 30% of total calories, including 6 ounces of pork on average per day – helped the women retain nearly double the amount of lean body mass (losing just 3.3 pounds of lean mass), compared to women who consumed the same amount of calories but ate less protein (losing 6.2 pounds of lean mass). The women in the study who consumed the higher protein diet also experienced less of a decline in satiety, or the feeling of fullness, which may be an additional benefit of a higher protein diet.

Source: Leidy H, Carnell N, Mattes R, Campbell W. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obes Res. 2007;15:421-429.