The protein source determines the potential of high protein diets to attenuate and reverse obesity development in mice
Speaker: Lise Madsen, Institute of Marine Research, Bergen, Norway, and Department of Biology, University of Copenhagen, Copenhagen, Denmark.
The notion that the obesogenic potential of high fat diets in rodents is attenuated by increasing the protein: carbohydrate ratio is largely based on studies using casein or whey as the protein source, whereas systematic studies using other protein sources are scarce. Feeding obesity-prone mice a high fat high protein diet using casein, soy, or filets of cod, beef, chicken or pork as protein sources showed striking differences in obesity development at thermoneutral conditions. Casein is the most efficient protein source in preventing weight gain and accretion of adipose mass, whereas mice fed high protein diets based on “white meat” (lean pork or chicken filets) gain the largest quantities of adipose tissue. Further, when already obese mice kept at thermoneutrality are shifted to high fat high protein diets, ad libitum feeding with a casein-based, but not a “white meat” -based diet, is able to reduce obesity. The casein-induced reduction in adiposity is associated with a reversal of the obesity-induced whitening of adipocytes in interscapular brown adipose tissue and induction of UCP1. Compared to other protein sources, casein seems to stand out by maintaining a β-adrenergic tone and a brown phenotype in interscapular brown adipose tissue with high UCP1 expression even at thermoneutrality. The type and level of other factors, such as fatty acids and persistent organic pollutants vary between dietary protein sources. All these factors can also modulate the composition of the gut microbiota and their obesogenic properties may thereby be influenced. Together, our results demonstrate that the ability of high protein diets to protect against and reverse obesity is highly dependent of the protein source.
Moderator: Jutta Dierkes