Nutritional amelioration of oxidative stress induced by obesity and acute weight loss

Obesity affects almost 50% of household pets. Excessive ingestion of highly palatable, nutritious food and an increasingly more sedentary life result in an accumulation of adipose tissue. Emerging evidence in human nutrition supports a link between the obese body condition, oxidative stress, and inflammation. Although the obese state promotes the production of damaging free radicals and inflammatory mediators, diet-induced weight loss may decrease these adverse sequelae. Controlled weight reduction protocols using high-protein (HP) versus high-carbohydrate (HC) interventions, commonly used as weight control strategies in humans and more recently in cats, have not been evaluated as to their total effect on health status. Our study investigated effects of diet (protein and carbohydrate [CHO]) and acute weight loss in obese cats on body composition, oxidative stress, and inflammation. Dietary treatments included an HP calorie-restricted diet (55% protein; 21% CHO; 8% fat; 3.4 kcal/g) and an HC calorie-restricted diet (37% protein; 46% CHO; 10% fat; 2.7 kcal/g) fed at 50% individual maintenance energy requirement (MER) for 12 weeks. Cats in both groups lost body weight (P <.0001) over the 12 weeks, with no difference by diet. Significant fat loss (P <.001) and lean tissue gain (P =.0039) occurred over time. Lean gain tended (P =.0781) to be more pronounced in HC cats in the first 6 weeks, but this advantage was lost from weeks 6 to 12. Oxidative stress-induced tissue damage (malondialdehyde, α1-antiproteinase, 8-OHdG) and inflammatory status (C-reactive protein, interlukin-6) were significantly improved in HP cats after weight loss compared with HC cats. Feeding an HP versus an HC diet to obese, healthy cats during acute weight loss minimizes oxidative damage to tissues, helps maintain lean body mass, and minimizes the inflammatory state, all of which are intuitively associated with a healthier state of weight loss.