Telling an obese person simply to eat less rarely succeeds. Is it because they are weak-willed individuals or is there something more complex going on?
New research indicates the latter. A new article in Cell Metabolism showed that during extreme calorie restriction, the levels of fatty acids begin to rapidly rise in the blood as the body begins breaking down stored fat for energy. These newly released fatty acids from the fat cells can then enter into the brain (the hypothalamus to be exact) and cause the self-digestion of cells in the hunger neurons (1). This self-digestion of the cells in the hunger neurons produces a rise in the very powerful hunger hormone (AgRP) from the same bundle of neurons. Not surprisingly, the urge to eat becomes almost overpowering. This begins to explain why very low calorie diets can cause rapid weight loss, but are rarely successful in keeping the weight off.
This is why very low calorie diets that promise quick weight loss invariably cause the rapid release of stored fatty acids that promotes constant hunger. This is clearly not a sustainable way to maintain long-term weight management.
Of course the question might be whether it is all fatty acids or just one that causes the problem of cellular death in the hunger neurons? I believe the answer comes back to the usual suspect, arachidonic acid (2). It has been known for 20 years that when you put obese individuals on a very low calorie diet there is a rapid increase in the levels of arachidonic acid levels in the blood (3). Arachidonic acid can easily cross the blood brain barrier and enter into the hypothalamus. Since arachidonic acid is a powerful promoter of cell death (4), increased concentrations inside the hypothalamus may be the primary accelerator of the death of the hunger neurons. Increased levels of arachidionic acid in the blood are also the underlying cause of insulin resistance because of its effect on the generation of cellular inflammation (2). So as you build up the levels of stored arachidonic acid in the fat cells, caused by the Perfect Nutritional Storm (2), you are almost ensuring constant hunger when you try to lose weight quickly by following very low calorie diets. To make matters even worse, as arachidonic acid levels also build up in the brain increasing the production of endocannabinoids (5). These are the hormones that give you the continual munchies (they are related to the active ingredient in marijuana).
So is there any good news in all of this research? Yes as long as you develop a lifetime dietary strategy for reducing arachidonic acid and the cellular inflammation it causes as well as following a reasonable low calorie diet that supplies adequate levels of fat to moderate the release of stored fatty acids from the fat cells. It means following an anti-inflammatory diet with adequate protein using low-glycemic load carbohydrates and fats very low in omega-6 fatty acids, but adequate in monounsaturated and omega-3 fats.
That’s why you never want to start any type of weight loss program without adding omega-3 fatty acids to counteract the released of stored arachidonic acid from the fat cells. Not only will these omega-3 fatty acids reduce the degradation of the hunger neurons thereby reducing the release of powerful hunger hormones during calorie restriction, but they will also inhibit the release of endocannabinoids in the brain (6). The combination of the two events will ensure weight loss without hunger and that’s sustainable.
- Kaushik S,Rodriguez-Navarro JA, Arias E, Kiffin R, Sahu S, Schwartz GJ, Cuervo AM, and Singh R. “Autophagy in hypothalamic AgRP neurons regulates food intake and energy balance.” Cell Metabolism 14: 173-183 (2011).
- Sears B. Toxic Fat. Thomas Nelson. Nashville, TN (2008).
- Phinney SD, Davis PG, Johnson SB, and Holman RT. “Obesity and weight loss alter serum polyunsaturated lipids in humans.” Amer J Clin Nutr 53: 831-838 (1991).
- Pompeia C, Lima T, and Curi R. “Arachidonic acid cytotoxicity: can arachidonic acid be a physiological mediator of cell death?” Cell Biochemistry and Function 21:97-104 (2003).
- Kim J, Li Y, and Watkins BA. “Endocannabinoid signaling and energy metabolism: A target for dietary intervention.” Nutrition 27: 624-632 (2011).
- Oda E. “n-3 Fatty acids and the endocannabinoid system.” Am J Clin Nutr 85: 919 (2007).