Nille sa for siden:
Drs. Atkins and Agatston, You Were So Right
Their low-carb diets are on target--control appetite, control weight
By Ricki Lewis
On January 20, I joined the ranks of those who've sacrificed themselves for science: I started one of those "low-carb" diets. So far, the sacrifice has been worth it.
I'd always resisted celebrity-sponsored diets, smugly thinking my
background in genetics and biochemistry made me more of an authority on matters nutritional than the likes of Whoopi Goldberg and Sarah Ferguson. I've even taught the subject.
But this low-carb diet is different. It prescribes "good carbs and good fats" while blacking out most things white and processed, including rice, bread, pasta, and potatoes. Building on conventional wisdom about the evils of excess starch, this program also considers insulin swings.
A new way of viewing carbohydrates began in 1981, when a University of Toronto team measured the glycemic index (GI) for many foods. The GI is a measure of the speed at which foods hike blood glucose and therefore insulin secretion, averaged in numerous individuals.1 A maximum for comparison purposes is either white bread or straight glucose. The idea is that rapid insulin fluctuation, as it shoves glucose into cells, sparks hunger.
GI numbers can be counterintuitive. For example, instant oatmeal sends insulin secretion skyrocketing, whereas whole oats do not, presumably due to digestion-slowing fiber. Even an unembellished baked potato becomes the enemy.
I had long wondered why following the US Department of Agriculture's food pyramid, which endorses a low-fat diet, plus daily exercise, had not vanquished a nanogram of me. Then my younger sister, a person who once wore size zero jeans, lost 10 pounds in two weeks following a low-carb diet. She left me no choice: I had to do it.
Day 1 was OK, my hypothalamus not yet registering glycogen depletion. By day 2, however, my head pounded, and all government-sanctioned painkillers were useless. Then I suddenly envisioned the glycolytic pathway and surreptitiously took a gulp of Pepsi; I felt instant relief. On day 4, I awoke feeling like aliens had replaced my body with a younger, more energetic model. Carb cravings vanished; pounds, too.
Months later, low-carb has become a way of life, even as my husband and daughter continue eating starchy foods, which I cook. I no longer want them. It's part metabolic, part psychological, a Pavlovian response linking a diet of mostly eggs, meat, cheese and certain vegetables with plummeting pounds, illogical as that may seem.
My husband the chemist and ex-marathoner, acknowledging his girth but unwilling to sacrifice pasta and potatoes, invented the NPCAD ("no potato chips after dinner") plan. His strategy: "I've eaten a lot of junk food all my life; now I don't." Being an XY without hormone issues, of course he's had little trouble shedding weight.
Considering my low-carb experience, I'd like to shed the USDA's food pyramid. I write textbooks, and the one I'm working on now carries this suspect guideline, with its broad bottom advocating those forbidden foods (the same ones the USDA oversees, grains), and the bulk of my present diet relegated to the "use sparingly" pyramid tip. Change is slow in textbook land, and my coauthors overruled my objections, this time around.
For years I, too, accepted the almighty pyramid, introduced in 1992, as dogma. When I taught nutrition, I preached that weight was a simple consequence of calories-in versus calories-out, food type unimportant. Because fats impart nine calories per gram compared to four for proteins and carbohydrates, with all intake being equal, fats were out. The fallacy is that all intake isn't equal. The glucose rush from refined carbohydrates does seem to intensify hunger inappropriately. In contrast, fats promote satiety. That's why mounds of spaghetti get polished off easier than large slabs of beef. So while calories-in must balance calories-out, eat fewer carbs and less will go in. The much-maligned Robert Atkins based his diet on the effects of appetite, and Arthur Agatston, who developed the South Beach Diet, iterated it. For me, evidence of friends shrinking on either diet, anecdotal as it is, convinced me that for some people, the USDA pyramid should be flipped.
Controlled studies are beginning to emerge. Two trials comparing
low-carb to low-fat declared the former the winner, for both weight loss and improved lipid profiles, within the first six months. After a year, such differences vanished, but many on the low-fat diet dropped out.2,3 However, these studies, like many previous ones, were too short and were limited to obese people. The prescription: more studies.
But I don't need them as proof. I'm unscientifically convinced with my sample of one. I've never felt better, and since January I've lost 25 pounds.
Ricki Lewis (ralewis~nycap.rr.com) is a freelance writer in Scotia,
NY.