Based on evidence that protein and fiber in food can influence satiety, a study was designed to assess their effect, alone or in conjunction, on diet in dogs. Diets were formulated containing 1) high protein and high fiber (HPHF), 2) high protein and moderate fiber (HP), and 3) moderate protein and high fiber (HF) and were evaluated for voluntary food intake as measured by energy consumption. Associated studies measured 1) voluntary intake during the first meal of the day, 2) short-term satiety when repeated exposure to food occurred during a 3-hour period, 3) medium-term satiety over a period of 3 hours, 4) long-term satiety over a period of 7 hours, and 5) satiety effect after an energy-restricted meal. During the short- and medium-term studies, the HPHF diet showed the greatest reduction in voluntary energy intake, suggesting a potential for greater compliance in weight-loss programs. None of the diets had a significant effect on intake in the long-term study, so reducing the number of hours between meals by splitting the daily ration over a number of meals may be necessary to increase compliance with a weight-reducing diet. The HPHF diet also had a satiating effect when fed at an energy-restricted level but whether it lessens when a restricted diet is fed continually is not known.  However, the favorable satiety characteristics of the HPHF diet suggest it would likely perform better than diets formulated as high in protein or fiber alone.

COMMENTARY: The HPHF diet in this study strikes a unique balance between palatability and ability to satisfy an animal's desire to eat, at least in the short term. When given a choice of 2 diets, there was no preference between the HPHF and the HP diet, but both were strongly preferred over HF. However, when a single diet was offered as a morning meal, dogs voluntarily consumed significantly fewer calories when fed HPHF vs HP. Further, desire for more food was supressed at least several hours when fed HPHF, an effect lost with twice-daily feeding. However, because the 3 commercial diets tested were manufactured by 2 companies, protein and fiber contents are difficult to compare across diets (eg, the fiber content of HPHF is much lower than in HF). Also, the diets notably varied in fat, nitrogen-free extract (carbohydrate), and calorie content as well as in major ingredients and types of fiber. Regardless, from a practitioner's perspective, the results may be compelling. Compliance issues (eg, extra treats, dogs stealing food) can be a major hindrance to successful weight loss. While further investigation is warranted, this study suggests that even a short-term effect on satiety may offer a potential advantage in the war on canine obesity.

A high-protein, high-fiber diet designed for weight loss improves satiety in dogs. Weber MI, Bissot T, Servet E, et al. J Vet Intern Med 21:1203-1208, 2007.