Clinical effects of high-fat meals and weight gain due to high-fat feeding

Abstract

Overfeeding high-fat (HF) meals results in both short-term and long-term effects that vary depending upon adiposity status (obese vs nonobese) and family history of type 2 diabetes. Although more than 4 weeks of overeating produces mild insulin resistance, whether the same is true of a single, HF meal is not clear. We reviewed overfeeding studies of 4–8 weeks duration, studies of single HF meals and our own (unpublished) plasma insulin and glucose concentration data from 59 nonobese and 15 overweight/obese volunteers who consumed either a normal-fat (NF) breakfast or a breakfast matched for carbohydrate and protein, but with an additional 80 g of monounsaturated fat (HF). Four to eight weeks of overfeeding a HF diet causes an ∼10% reduction in insulin sensitivity. Some authors report that a single HF meal is associated with greater postprandial insulin concentrations, whereas other investigators have not confirmed such a response. We found that plasma glucose concentrations peaked later following a HF breakfast than a NF breakfast in both obese and nonobese adults and that daytime plasma insulin concentrations were not uniformly increased following a HF breakfast. We conclude that a single HF meal delays the postprandial peak in glucose concentrations, likely due to delayed gastric emptying. This will confound attempts to use insulinemia as a marker of insulin resistance. After 4–8 weeks of overeating a HF diet accompanied by 2–4 kg of fat gain, insulin sensitivity decreases by ∼10%. Although we could not demonstrate that baseline insulin resistance predicts visceral fat gain with overfeeding, normal-weight relatives of type 2 diabetes mellitus do tend to gain more weight and become more insulin resistant than those without a positive family history of type 2 diabetes mellitus. In summary, short-term weight gain from HF diets induces relatively mild metabolic disorders.