- The nutrition of 200 patients after Roux-en-Y gastric bypass for morbid obesity was followed for 6.7 years. During the first 2 years their food intake was severely restricted, resulting in an excess weight loss of 69 +/- 14%. At an average of 3 years after surgery they began to regain weight significantly (p less than 0.04) due to nutritional adaptation. In the following years caloric consumption stabilized at an excess weight loss of 48-56%. However, they had continuing meat intolerance with 51.0, 60.3, 59.5 and 55.1% of them avoiding meat during 0-12 months, 13-24 months, 25-72 months and 73-96 months after surgery, respectively. We conclude that after Roux-en-Y gastric bypass there is nutritional adaptation lasting as long as 2 years, when a characteristic nutritional behavior is adopted which persists for years.