06/03/2025
The Study
This 60-day study involved 135 non-exercising obese people and compared three different diets. Participants were divided into groups:
High-Protein Diet – These folks consumed 30% protein, 40% carbs, and 30% fats, with a 500-750 calorie daily deficit. Protein was approximately 0.73 to 0.91 grams per pound of body weight, and they were provided with protein powder to hit their numbers.
Calorie Restriction – This group followed a "balanced" macronutrient diet: 15% protein, 55% carbs, 30% fat, also with a 500-750 calorie daily deficit.
Intermittent Fasting – This group followed a 5/2-style plan. They ate normally (balanced diet, 15% protein) for five days and restricted intake to 500-600 calories (high-carb, low-protein) on two non-consecutive days per week, achieving a similar weekly calorie deficit as the other groups.
All subjects underwent DEXA testing and a variety of blood tests.
What Happened?
Short answer: High protein outperformed lower-protein calorie restriction and intermittent fasting:
Weight Loss: The high-protein group lost an average of 15 pounds compared to 11.5 pounds for calorie restriction and 10.8 pounds for intermittent fasting.
Fat Mass Reduction: The high-protein group reduced fat mass by 13 pounds compared to 9 pounds for calorie restriction and 8.4 pounds for intermittent fasting.
Lean Mass Preservation: The high-protein group lost only 2 pounds of lean mass compared to 2.4 pounds for calorie restriction and 2.6 pounds for intermittent fasting.
Cardiometabolic Benefits: The high-protein group saw greater improvements in triglycerides (-22%), fasting glucose (-10%), and insulin (-18%) compared to calorie restriction and intermittent fasting.
Satiety: The protein group reported more fullness and less hunger than the other groups.
In short, the protein eaters lost more fat (especially from the visceral/belly area) and preserved more muscle mass (remember, they weren't lifting).