In rats fed high-energy diets, taste, rather than fat content, is the key factor increasing food intake: a comparison of a cafeteria and a lipid-supplemented standard diet.

Laia Oliva,Anna Fernández-Bernal,Tània Aranda,Marià Alemany,José Antonio Fernández-López,Giada Caviola,Xavier Remesar

doi:10.7717/peerj.3697

Abstract

BackgroundFood selection and ingestion both in humans and rodents, often is a critical factor in determining excess energy intake and its related disorders.MethodsTwo different concepts of high-fat diets were tested for their obesogenic effects in rats; in both cases, lipids constituted about 40% of their energy intake. The main difference with controls fed standard lab chow, was, precisely, the lipid content. Cafeteria diets (K) were self-selected diets devised to be desirable to the rats, mainly because of its diverse mix of tastes, particularly salty and sweet. This diet was compared with another, more classical high-fat (HF) diet, devised not to be as tasty as K, and prepared by supplementing standard chow pellets with fat. We also analysed the influence of sex on the effects of the diets.ResultsK rats grew faster because of a high lipid, sugar and protein intake, especially the males, while females showed lower weight but higher proportion of body lipid. In contrast, the weight of HF groups were not different from controls. Individual nutrient’s intake were analysed, and we found that K rats ingested large amounts of both disaccharides and salt, with scant differences of other nutrients’ proportion between the three groups. The results suggest that the key differential factor of the diet eliciting excess energy intake was the massive presence of sweet and salty tasting food.ConclusionsThe significant presence of sugar and salt appears as a powerful inducer of excess food intake, more effective than a simple (albeit large) increase in the diet’s lipid content. These effects appeared already after a relatively short treatment. The differential effects of sex agree with their different hedonic and obesogenic response to diet.

Highlights

Fat intake is correlated with weight gain and increased body fat content (Rothwell & Stock, 1984)
A wide variety of high-energy diets have been used, in which the high lipid content is the common link, indicating that dietary fat is a critical factor for fat accumulation (Buettner, Schölmerich & Bollheimer, 2007)
The gain in weight shown by the HF-diet fed animals was similar to that of controls on fed standard food pellets, and agrees with data previously described for rats of the same-age kept on a standard diet (Buettner, Schölmerich & Bollheimer, 2007; Martire et al, 2013), the results were influenced by sex

Summary

Introduction

Fat intake is correlated with weight gain and increased body fat content (Rothwell & Stock, 1984). Cafeteria diets (K) were self-selected diets devised to be desirable to the rats, mainly because of its diverse mix of tastes, salty and sweet This diet was compared with another, more classical high-fat (HF) diet, devised not to be as tasty as K, and prepared by supplementing standard chow pellets with fat. The results suggest that the key differential factor of the diet eliciting excess energy intake was the massive presence of sweet and salty tasting food. The significant presence of sugar and salt appears as a powerful inducer of excess food intake, more effective than a simple (albeit large) increase in the diet’s lipid content. These effects appeared already after a relatively short treatment. The differential effects of sex agree with their different hedonic and obesogenic response to diet

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