Weight and metabolic changes induced by low carbohydrate-high fat diets in man and in rat

Weight loss and potential toxicity of low carbohydrate-high fat diets were examined in 8 volunteer medical students given either a high fat diet or a high carbohydrate diet for 15 days, as well as in 36 Sprague-Dawley rats fed for 5 weeks a series of low carbohydrate diets (less than 1%), varying in protein and lipid proportions. A weight loss occurred with the low carbohydrate-high fat diets; serum cholesterol level increased in both man and rat; plasma triglycerides rose in man. In rat, we found an increase in hepatic lipid levels as in plasma ketone and non-esterified fatty acid concentrations. These effects seemed to be related to the increase in lipid intake rather than the lack of carbohydrates.