If you want to lose weight and ward off diabesity, you "supplement" with red meat!
In their 24 week trial, Chen et al. kept a group of 24 male Wistar rats, who had been pre-fattened on the standard SAD-like "high fat diet" for 14 weeks (an interesting side note: only 24 of the 46 rats who received the HFD diet got actually obese, i.e. they gained +20% more body-fat than their peers - so what does that tell you about the "general" fattening effect of the "high fat diet"?) on either
- regular rodent chow with 67.8% of energy from carbohydrates, 12.8% fat and 19.4% protein, or
- red-meat enriched "high" protein diets with 46.6% of energy from carbohydrates, 16.7% fat and 36.7% protein
|Figure 1: Body weight (in g) during and visceral fat (in g) after 24 weeks on high protein meat or normal protein chow diets (data adapted from Chen. 2012)|
|Figure 2: Insulin AUC during intravenous glucose tolerance test (IGGT) and fasting GLP-1 levels |
(data adapted from Chen. 2012)
Why the different results? Don't tell me meat is not bad for me!
Aside from the questionnaire based epidemiological studies, where "Pizza Salami" is a "red meat food", I mentioned earlier, there definitely is experimental data (on which the working hypothesis of many of the epidemiological studies are founded, by the way) that would suggest that feeding red meat to rodents is not the best thing to do... now, if we discard species-specific issues for the time being, how can those differences be explained? Chen et al. provide a pretty straight-forward set of potential confounding factors in their discussion, which I am going to summarize for you:
- meat is an energetically denser protein source than dairy - this may explain why, compared to dairy products, meat has been found to be positively associated with weight gain in rats (eg. Belobrajdic. 2003)
- the longer experimental duration - in previous studies there were already "tendencyies toweight loss" at the end of the mostly 10-12 week study periods
- the age of the animals may have a profound effect on the weight gain; for rats that are younger than the ones in the study at hand, an increased weight could would in fact indicate a healthy effect during the most active growth period of the rodents rats; this would not preclude, though that the same diet would facilitate weight loss in mature rats