Recovery of insulin sensitivity and optimal body composition after rapid weight loss in obese dogs fed a high‐protein medium‐carbohydrate diet
With respect to glucose intolerance and reduced insulin sensitivity, approaches that use low glycaemic index diets have been tested to improve weight and metabolic outcomes (Mitsuhashi et al., 2012). Foods with low glycaemic index may also reduce oxidative stress and protect the cardiovascular system in dogs (Adolphe et al., 2012). The glycaemic index was developed to rank carbohydrate‐containing foods according to their effects on blood glucose levels in humans (Jenkins et al., 1981). Rapidly available glucose (RAG) is defined as the amount of glucose released in vitro from a food during the first 20 min of incubation with adequate enzymes, and it has been shown to be related to the glycaemic response in human studies (Englyst et al., 1999). In rats, both plasma glucose and insulin responses were positively correlated to the rate of hydrolysis with α‐amylase in vitro (Holm et al., 1988). However, a more recent human study showed that two carbohydrate sources with similar RAG content elicited similar glycaemic responses but different insulin responses (Al‐Mssallem et al., 2011). Thus, predicting the effects of a diet on postprandial plasma glucose and insulin kinetics is not easy, and field trials in target species are necessary to accurately evaluate the in vivo responses.
In dogs, postprandial glucose kinetics are mainly influenced by the amount of starch in the diet (Nguyen et al., 1994). Nevertheless, many factors other than available carbohydrate level affect postprandial glycaemia and insulinaemia, including starch source and structure, macronutrient content and source (Kendall et al., 2006). In particular, it has been shown, in humans, that high protein intake increases insulin secretion (Gulliford et al., 1989), and moreover that different sources of protein may lead to different insulin responses (Nuttall and Gannon, 1990).
Compared to the starch level, the protein level has a limited impact on postprandial glycaemia, but there has long been interest in the use of high‐protein diets for weight loss. Orthopaedic or other surgical procedures may require weight loss, either for causal reasons (orthopaedic procedures) or because obesity makes anaesthetic management more difficult or is a risk factor for surgical site infections (Love and Cline, 2015). Therefore, high‐energy restriction may be chosen when there is a medical indication for rapid weight loss. In dogs, energy restriction is suggested for losses of 1%–2% of the initial body weight (BW) per week (Nguyen and Diez, 2010). In all cases, it takes months to lose the excess 25%–30% of excess BW that is, the weight over the optimal BW. Although the literature is not entirely conclusive on this point, in general, the risk of losing lean body mass is higher with a higher rate of weight loss.