ABSTRACT: Successful treatment and prevention of overweight and obese cats and dogs require a multidimensional approach to ensure causes or exacerbating factors are identified and eliminated, professional examination and care are provided on a regular basis, and a comprehensive management program is planned and implemented. Over the years, many therapeutic and preventive interventions have been developed or advocated for obese animals, but evidence of effectiveness is often lacking or highly variable. Accordingly, the primary objective of the information reported here was to identify and critically appraise the evidence supporting various aspects of managing obese and overweight pet animals. (Roudebush P, Schoenherr WD, Delaney SJ. An evidence-based review of the use of nutraceuticals and dietary supplementation for the management of obese and overweight pets. JAVMA, Vol 232, No. 11, June 1, 2008)
COMMENTARY: This interesting review article assesses the evidence for various supplements that have been advocated for weight loss, and whether they might be useful in pets. The supplements are actually rated according to their supporting scientific evidence. The rating scale looks like this:
Grade I - Evidence obtained from at least 1 properly randomized, controlled clinical study that used the nutritional product in the target species (dogs, cats - not lab animals or people) with animals that had developed the disease naturally. Data published in peer-reviewed journals are preferred.
Grade II - Evidence obtained from randomized, controlled clinical studies conducted in a laboratory setting that used the nutritional product in the target species with animals that had developed the disease naturally. Data published in peer-reviewed journals are preferred.
Grade III - Evidence obtained from 1 or more of the following:
–At least 1 appropriately designed clinical study without randomization
–Cohort or case-controlled analytic studies
–Studies that used acceptable models of disease or simulations in the target species
–Dramatic results from uncontrolled studies
Data published in peer-reviewed journals are preferred.
Grade IV - Evidence obtained from 1 or more of the following:
–Opinions based on clinical experience (textbooks, monographs, or proceedings)
–Studies conducted in other species
–Reports of expert committees
Here is the report card for weight loss supplements:
Pyruvate: an unpublished grade II study in dogs found that pyruvate supplementation did NOT enhance weight or fat loss in overweight dogs consuming a low-fat food. There is no data in cats.
Omega 3 fatty acids: one unpublished grade II study suggests that increased consumption of
omega-3 fatty acids may be beneficial in overweight dogs on calorically restricted diets.
Amylase inhibitors (starch blockers): only a pathophysiologic rationale (ie, grade
IV evidence) exists to support use of compounds that delay carbohydrate absorption.
DHEA: grade II studies in obese dogs suggest that DHEA may be beneficial as part of a weight management program when used with calorie-restricted foods. DHEA is not recommended because of adverse effects, and newer, safer forms have not been tested in dogs or cats.
L-carnitine: grade I and II studies suggest that l-carnitine supplementation of weight management foods can benefit obese and obesity-prone cats and dogs.
Conjugated linoleic acid (CLA): seems to help reduce fat vs lean body weight in growing animals but there is little evidence that it is useful in weight loss programs for adults.
Phytoestrogens: results of Grade II studies indicate that genistein may help prevent obesity after neutering cats, and limited, unpublished data support the use of soy isoflavones for preventing weight gain in dogs.
Diacylglycerol: Grade II studies in dogs suggest that diacylglycerol may enhance fat loss.
Chromium: Grade II studies tend to show that chromium does not assist in weight loss for either dogs or cats.
Vitamin A: grade II studies indicate that vitamin A supplementation may help blunt increases in body weight in cats and dogs allowed ad lib consumption of high-fat foods.
Authors' conclusion: "On the basis of this grading system, the best evidence exists for use of dietary l-carnitine supplementation in obese or overweight pets, although many of the results for use of l-carnitine are described only in abstracts, industry publications, and patent applications, which makes it difficult to review experimental methods and data analysis. More research-based evidence is needed to support routine use of other nutraceuticals or dietary supplementation, with compounds such as pyruvate, amylase inhibitors, safer forms of DHEA, CLA, diacylglycerol, chromium, and vitamin A, for weight loss in pets.