RAS, Low-Carb Diets and NEAT

This morning, on the last day of the 2010 EASD in Stockholm, I co-chaired the Michael Berger debate on whether or not blocking the renin-angiotensin system is the be all and end all of organ protection. The debaters were Bo Feld-Rasmussen from the University of Copenhagen and Andrea Natali form the University of Pisa, Italy.

As is common in such debates the debaters ended up agreeing on most aspects of this question, barely agreeing to disagree on the 5% of aspects that remained controversial. Clearly, there is more to preventing end organ damage than simply blocking the renin angiotensin system – in fact, it may in the end not really matter all that much, how blood pressure is lowered after all, at least when it comes to protecting renal function in patients with type 2 diabetes.

Yesterday, as readers may recall, I gave an invited plenary lecture on my etiological assessment of obesity.

My talk, was immediately followed by Eric Wesman from Duke University, who talked about ketogenic low-carb diets, which he uses effectively for obesity treatment.

As Wesman explained, the principal rational for the use of low-carb diets is that they help reduce insulin levels, thereby allowing the body to access energy stores. As readers may recall, insulin is a potent “fat blocker” in that it not only promotes fat storage but also makes it more difficult for fat to be released from fat stores.

Thus in a randomised trial comparing a low-fat, a Mediterranean, and a low-carb diet, the latter resulted in the greatest weight loss, at least initiatlly. Furthermore, although participants may not have significantly differed in their weight loss at the end of a year, they low-carb participants appeared to have sustained imporvements in lipid status.

Several other studies have now also demonstrated that low-carb diets in patients with diabetes may result in better glycemic control.

Obviously, not everyone can follow these diets and therefore the average results seen in such studies may not be representative of the excellent results that Wesman sees in the patients who actually do manage to stay on these diets over time (remember: diets don’t work in people who don’t stick with them).

Thus, Wesman concludes that low-carb ketogenic diets are both feasible and effective for people who want to do them and can stick with them. But they obviously only works for people who truly enjoy cutting out their carbs – if this is perceived as a sacrifice or the temptation to eat carbs is too great (depression?) then it is obviously not the right diet for that person.

Wesman was followed by Jim Levine from the Mayo Clinic who published the original studies on the importance of non-exercise activity thermogenesis (NEAT) as a key determinant of energy spent in every day living. Both feeding and immigration studies have shown that NEAT is an important factor that helps lean people regulate their body weight.

In his talk he discussed the various strategies that he (and his company) now uses to promote non-exercise activity like walking desks, walking meetings and other ways to (re-)introduce physical activity into everyday school and office life.

Thus, three very different talks on obesity in this session, covering the whole spectrum of individualised assessments and dietary intervention to physical activity.

Stockholm, Sweden

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Shai I, Schwarzfuchs D, Henkin Y, Shahar DR, Witkow S, Greenberg I, Golan R, Fraser D, Bolotin A, Vardi H, Tangi-Rozental O, Zuk-Ramot R, Sarusi B, Brickner D, Schwartz Z, Sheiner E, Marko R, Katorza E, Thiery J, Fiedler GM, Blüher M, Stumvoll M, Stampfer MJ, & Dietary Intervention Randomized Controlled Trial (DIRECT) Group (2008). Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. The New England journal of medicine, 359 (3), 229-41 PMID: 18635428