High Protein Diets Are Best for Weight Loss in Cats

By Jennifer Coates, DVM on Jul. 24, 2015

Fat cats — they seem to be everywhere (at least to vets). We all know that if fat cats are to enjoy good health and a long life, we need to help them lose weight. But what type of food is best suited to make that happen? A couple of recent studies help answer that question.

In the first, researchers looked at what effects giving fat cats free access to either a high protein [47% of metabolizable energy (ME)] or moderate protein (27% of ME) diet for four months would have on the following parameters:

Energy intake
Body weight
Body composition
Energy expenditure
Concentrations of hormones and metabolites associated with carbohydrate and lipid metabolism (glucose, insulin, free fatty acids, triglycerides and leptin)

They found that the cats who ate the high protein diet burned more calories (adjusted for body weight or lean body mass) than did the cats who ate the moderate protein diet.

Unfortunately, the “high protein” cats also ate more, so in the end there was no significant difference in the two group’s body weight or in most of the other parameters. But the authors did state that since the fat cats eating the high protein diet did burn more calories, it is possible that a high protein diet “might help promote weight loss when energy intake is restricted.”

That’s just what the second study investigated. For two months, sixteen overweight cats were fed either a high protein (54.2% of ME) or moderate protein (31.5% of ME) diet at 70% of their “maintenance energy intakes.” The researchers found that “while both groups of cats lost weight at a similar rate, only cats eating the HP diet maintained lean mass during weight loss.” Also, when the cat’s body weight or lean body mass was taken into account, the cats eating the MP diet burned fewer calories than did those eating the HP diet. All this led the authors to conclude:

Results from this study suggest that in addition to sparing the loss of lean mass, feeding HP diets to overweight cats in restricted amounts may be beneficial for preventing or minimizing decreases of mass-adjusted energy expenditure during weight loss.

The take home message? While cats can lose weight on almost any diet as long as we restrict their intake sufficiently, high protein diets help them maintain the muscle mass needed to keep them burning those calories.