Under blue skies and enjoying cool ocean breezes in San Diego, CA, the Endocrine Society is currently holding their annual gathering, ENDO, and mulling over the latest research. This year most of the talk is about insulin, insulin resistance and weight control. New studies are being reviewed daily, including one funded by none other than Jenny Craig.
The Jenny Craig funded study looked at diet composition and weight loss. Raymond Plodkowski, MD, and his colleagues at the University of Nevada, Reno, placed women with documented insulin resistance on either a low-fat or low-carbohydrate diet. (His Comment: Ultimately all people who are significantly overweight will become resistant to their own insulin eventually.) What they found was that even with a conservatively low-carbohydrate diet that these women lost more weight dodging the carbs and worrying less about the fat. The low-carb diet group lost 21 percent more weight over 12 weeks than the low-fat diet group.
That may not be surprising news to Adkins’ and paleo diet advocates, but it does beg the question where does insulin resistance start? Like many things, it can begin in childhood. According to research by Georgina Coade, a PhD student at the University of Bristol, fructose is part of the problem. Fructose she found results in changes in fat cells, specifically visceral fat (that’s fat covering organs inside the abdomen). The fat cells become more mature and less responsive to insulin. That lack of responsiveness makes them less likely to release fat and makes the fat cells less metabolically active.
Turning around insulin resistance is hard, but Antonio Mancini, MD, an endocrinology researcher at Catholic University of the Sacred Heart in Rome, found that antioxidants in the diet can improve insulin resistance. His work found that a diet high in fruit and vegetable based anti-oxidant vitamins resulted in more improvement in insulin resistance and more weight loss whether medications were involved in the equation or not.
His Take: If you’re not familiar with insulin resistance and why it matters metabolically, the wikipedia article is a great summary. Almost every person with long term weight becomes insulin resistant and many people who carry obese levels of weight become resistant in a very short period of time. Clinically, I’m not yet measuring insulin levels in all of my patients for their annual exam but I’m getting close to it. Insulin resistance cuts to the core of how overweight and obesity adversely impact health over time since many of the other negative health changes that follow cascade from insulin resistance. Cranking down on the carbs, dodging the fructose and upping diet anti-oxidants should be routine for everybody but especially for people who have weight issues to have a real chance at aging against the machine.
Her Take: One thing that struck me about the Jenny Craig study was that it was only a very light carbohydrate restriction. The “low fat” diet was 65% carbohydrate, while the “low carb” diet was 45% carbs. If this was a 1500 calorie per day diet, that amounts to 168 grams of carbohydrates a day. This is substantially higher than any traditional low carb diet out there today, and yet people still lost more weight than the low fat diet. It shows that even moderate carbohydrate restriction can help dieters lose weight.