Objective: The objective of this study was to examine if increased protein intake vs. control influences body fat percentage during stable body weight. Design: Body composition was assessed before and after a 3-month isoenergetic dietary intervention of 2MJ/d supplements exchanged with 2MJ/d of habitual ad libitum energy intake. The parallel design consisted of protein-rich supplements in the protein group (n= 12) and an isoenergetic combination of carbohydrate and fat supplements in the control group (n= 12). Daily protein intake was calculated from a 24. h urinary nitrogen. Body composition was measured by a combination of underwater-weighing technique, deuterium-dilution technique and whole-body dual-energy X-ray absorptiometry (DXA), a method that allows for estimation of 4-body compartments (fat and lean; water, bone and rest). Results: Subjects were weight stable and did not change their habitual physical activity. Daily protein intake increased in the protein group during the intervention compared to baseline with +. 11 ± 14. g (P< 0.05) vs. the control group that did not change their protein intake -1 ± 15. g. This resulted in a significant difference in protein intake during the intervention of 80 ± 21. g of the protein group vs. 59 ± 11. g of the control group (P< 0.01). Change in body fat percentage showed a significant group × time interaction of decreased body fat percentage of -1.0 ± 1.1% of the protein group vs. 0.1 ± 0.6% of the control group (P< 0.05). The group × time interaction of change in fat mass was significant (P< 0.05), and change in fat-free mass was a trend (P= 0.05). Fat-free mass of the protein group had increased with +. 0.9 ± 0.6. kg (P< 0.01), and fat mass had decreased with -0.6 ± 0.8. kg (P< 0.05), while the control group had not changed. Conclusion: During increased daily protein intake vs. control body fat percentage decreased with unchanged physical activity during 3. months of stable body weight.