As with other diet plans, people who maintain a low-carbohydrate diet lose weight. In the case of low-carbohydrate diets, weight loss is helped by the increased feeling of fullness and a tendency towards selecting nutrient-rich food. A very low-carbohydrate diet performs slightly better than a low-fat diet for long-term weight loss. The long-term effects of a low-carbohydrate diet are not known.
Limiting carbohydrate consumption is a traditional treatment for diabetes – indeed, it was the only effective treatment before the development of insulin therapy – and when carefully adhered to, it generally results in improved glucose control, usually without long-term weight loss. Some experts recommend a low-carbohydrate diet as the first, default treatment for people with diabetes. There is mixed evidence to support the use of low-carbohydrate diets for people with diabetes in the short-term, but no good evidence of long-term benefit or safety. Safety is a concern if the diet is taken without expert monitoring.
Potential favorable changes in triglyceride and high-density lipoprotein cholesterol values should be weighed against potential unfavorable changes in low-density lipoprotein cholesterol and total cholesterol values when low-carbohydrate diets to induce weight loss are considered. A 2008 systematic review of randomized controlled studies that compared low-carbohydrate diets to low-fat/low-calorie diets found the measurements of weight, HDL cholesterol, triglyceride levels, and systolic blood pressure were significantly better in groups that followed low-carbohydrate diets. The authors of this review also found a higher rate of attrition in groups with low-fat diets, and concluded, “evidence from this systematic review demonstrates that low-carbohydrate/high-protein diets are more effective at six months and are as effective, if not more, as low-fat diets in reducing weight and cardiovascular disease risk up to one year”, but they also called for more long-term studies.