This is the continuation of our exploration of how the fats that we eat affect our brain’s ability to control our appetite, which is particularly important when a person is trying to lose weight fast. Have you missed the first part of this article? In this second part, we explore some recent research that suggests that saturated fat (as opposed to unsaturated fat) interferes with the signals that allow the brain to control appetite. This potentially impacts how people following a low-carb diet like the South Beach Diet plan their meals.
Dietary Fat, Palmitic Acid, and Appetite Control
In a September 2009 study titled “Palmitic acid mediates hypothalamic insulin resistance…” (Published in the Journal of Clinical Investigations, Vol. 119, Number 9), Stephen Benoit et al. note that diets high in some kinds of saturated fats interfere with insulin and leptin reactions, while the opposite seems to happen in diets with unsaturated fats. The authors report that their research shows that palmitic acid (which is in many foods such as butter and cheese, as well as meat) interferes with insulin signals – interfering with the brain’s ability to react appropriately to moderate food intake. What’s even more interesting is that the authors report that this type of action is unique to palmitic acid, and that other types of fatty acids do not have such an effect. The authors cite a 2002 study by Silvana Obici et al., published in Diabetes (The Journal of the American Diabetes Association, 2002) that concluded that oleic acid (contained in olive oil) suppresses appetite by mimicking some of the effects of insulin and leptin. (For more discussion of leptin, please see our prior article Raisins, Appetite Control and Weight Loss.)
Fat, Leptin and Insulin Resistance
Remember that very few things are cut-and-dry, especially when it comes to a very complex bio system like the body, and that even “conclusive” scientific studies may reveal only a part of the puzzle. However, this research does suggest that palmitic acid (e.g. more cheeses, butter, meats) interferes with natural appetite control. If there is a greater chance of eating more food than needed because that food contains palmitic acid (which reduces the strength of the chemical signals delivered to the brain), it stands to reason that minimizing sources of palmitic acid in one’s diet may help to control appetite better. And, better appetite control generally means losing weight fast, and better overall diet results.
The Benoit et al. study was conducted on rats, and the major variation between the study groups was the amount and type of fat being provided to the rats. The authors state that
“…it has been demonstrated that diets high in monounsaturated fatty acids (oleic acid) prevent dietary fat-induced insulin resistance, whereas diets high in palmitic acid accelerate obesity.”
(The Journal of Clinical Investigation, Vol. 119, Number 9, p. 2577)
Concluding Thoughts on Low Carb Diets, Weight Loss and Fat
Recent Science seems to support the idea that low-carb diets appear to be effective in initial weight loss, as well as an ability to keep the weight off through control of carbohydrates. The consensus of several research efforts seems to conclude that low-carb diets are at least as effective as low-fat diets (and generally, there is evidence to believe that low-carb diets have a small edge if factors such as the total amount of weight loss, losing weight quickly, or ability of people to stay on the diet).
There is some disagreement between the “original” low carb diet (Atkins, which was designed in the 1970s), and later variants like the South Beach Diet, and the principal difference seems to be the approach that not all fat is the same. This research seems to support that idea. In all, fat is but one of the variables in the complex system called the human body, and the success of losing weight on a diet. But it is interesting to note that by making small changes, such as switching from saturated fat like butter to unsaturated fat like olive oil or non-butter spreads could potentially improve dietary results (not to mention general health).
References and Additional Resources
20BMI.com Nutrition Category
20BMI.com’s Review of the South Beach Diet (the book)
Journal of Clinical Investigations
Journal of the American Diabetes Association
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