Obesity is a major health problem in cats and a risk factor for diabetes. It has been postulated that cats are always gluconeogenic and that the rise in
obesity might be related to high
dietary carbohydrates. We examined the effect of a high-
carbohydrate/low-
protein (HC) and a high-
protein/low-
carbohydrate (HP) diet on
glucose and fat metabolism during euglycemic hyperinsulinemic clamp,
adipocytokines, and fat distribution in 12 lean and 16 obese cats before and after
weight loss. Feeding diet HP led to greater heat production in lean but not in obese cats. Regardless of diet, obese cats had markedly decreased
glucose effectiveness and
insulin resistance, but greater suppression of
nonesterified fatty acids during the euglycemic hyperinsulinemic clamp was seen in obese cats on diet HC compared with lean cats on either diet or obese cats on diet HP. In contrast to humans, obese cats had abdominal fat equally distributed subcutaneously and intra-abdominally.
Weight loss normalized
insulin sensitivity; however, increased nonesterified
fatty acid suppression was maintained and fat loss was less in cats on diet HC.
Adiponectin was negatively and
leptin positively correlated with fat mass. Lean cats and cats during
weight loss, but not obese cats, adapted to the varying
dietary carbohydrate/
protein content with changes in substrate oxidation. We conclude that diet HP is beneficial through maintenance of normal
insulin sensitivity of fat metabolism in obese cats, facilitating the loss of fat during
weight loss, and increasing heat production in lean cats. These data also show that
insulin sensitivity of
glucose and fat metabolism can be differentially regulated in cats.