In an effort to clear up the considerable confusion about which diet is most effective for fat loss, researchers from Stanford University spent a year testing four popular diet plans on 311 overweight women, aged 25 to 50. Published in the prestigious Journal of the American Medical Association, the study examined the Atkins low-carb plan, which starts at 20 grams a day of carbs and gradually increases to 50 grams a day; the Zone diet, which features a percentage formula of 40-30-30 for carbs, protein and fat; the LEARN plan, a traditional balanced diet usually suggested for promoting good heath, consisting of 55 to 60 percent carbs and less than 10 percent saturated fat intake; and the Ornish diet, which contains 10 percent fat or less. The Zone and LEARN plans call for a specific daily calorie limit, while the Atkins and Ornish plans don’t.
The greatest criticism of low-carb diets is that their high fat content predisposes dieters to cardiovascular disease. That was adamantly denied by Robert Atkins, M.D., the heart specialist who developed the Atkins diet. Atkins suggested that control of insulin, a cornerstone of low-carb diets, would more than make up for eating lots of fat. Besides, because carbs are so restricted on the Atkins plan, most of the dietary fat is oxidized.
Dean Ornish, also a cardiologist and whose diet philosophy is the opposite of Atkins when it comes to eating fat, noted that levels of low-density lipoprotein, or LDL, which is linked to cardiovascular disease, rose in those who followed a low-carb diet during the study. As one of the authors noted, however, blood triglycerides dropped more than 30 percent in the low-carb dieters. That’s significant because when triglycerides drop, you get a larger, more buoyant LDL molecule. The type of LDL linked to cardiovascular disease is small and dense and is more likely to oxidize than the larger version. LDL is dangerous only when oxidized.
Other critics of the new study said that while those on the Atkins diet clearly lost more fat initially, after a year the differences in fat loss from the diets become similar. The women on the Atkins plan found it easy to follow, with no precise guidelines other than carb restriction. The high-protein feature of the Atkins diet brings greater satiety, making it far easier to stick with than lowfat, high-carb diets like the Ornish plan, on which most people get ravenously hungry.
Those in the Atkins group also had elevations in high-density-lipoprotein cholesterol, which protects against cardiovascular disease. HDL tends to rise with a higher fat intake, an effect confirmed with those who followed the Ornish lowfat plan. No change at all occurred in their HDL levels, although LDL did drop.
Because most people diet to lose bodyfat, it’s just common sense that the diet with the best results would be more motivating. Losing fat is important for health reasons because excess bodyfat triggers inflammation all over the body that’s linked to all forms of disease and mortality, including cardiovascular disease and cancer.
Bodybuilders used low carb-diets long before they became popular with the public. In fact, most top bodybuilders still rely on carb restriction to get into contest condition. They know that when you control insulin release, you rapidly tap into bodyfat stores. It’s true that glycogen, which is the major exercise fuel source in muscles, is itself a complex carbohydrate, but it’s not that difficult to take your carbs in strategically, meaning before and after training. That makes for maximum fat burning while providing needed energy.
Gardner, C.D., et al. (2007). Comparison of the Atkins, Zone, Ornish and LEARN diets for change in weight and related risk factors among overweight women. JAMA. 297:969-77.
©,2013, Jerry Brainum.Any reprinting in any type of media, including electronic
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