Your dietitian is misleading you. That’s the takeaway from an article published recently in the medical journal The Lancet. The rules of thumb that you’ve been given are wrong. And losing weight quickly and easily by cutting a few hundred calories a day just doesn’t happen, scientists say.
Dieters are often told that if they cut 500 calories a day, they will lose a pound a week. How much is 500 calories? It’s the equivalent of a single quarter-pounder with cheese from McDonald’s or a small serving of pasta with sauce and bread. But scientists say such a reduction would not lead to the advertised quick weight loss — roughly 50 pounds in a year if maintained. Instead, the article says that a 50-pound loss would take three years or longer.
The news may sound discouraging, but it actually makes sense.
Think about it this way: Our bodies adjust to the amount we eat. If we consume more calories, we have more energy to burn off. But if we eat less — as we do when we diet — we have less energy. The body wants to establish some sort of stasis.
Kevin D. Hall of the National Institute of Diabetes and Digestive and Kidney Diseases was the lead author of the study, and he and fellow researchers put together an alternative rule of thumb for dieters. But be warned: It looks at the long term.
If you consistently reduce your food intake by 24 calories each day, you’ll eventually lose 2.2 pounds, Hall said. In other words, cutting roughly 500 calories a day will eventually lead to about 50 pounds of weight loss. But the weight loss takes time — only half of those 50 pounds would come off in the first year. You have to maintain the diet for two more years to lose most of those 50 pounds.
The researchers are sounding the alarm. They want people to know that weight loss isn’t as simple or quick as portrayed by many in the public health community. “We suggest,” they wrote, “that unrealistic weight loss expectations obtained by erroneous use of the static dieting rule should be replaced by our methods to assess other population-wide and more targeted obesity prevention interventions.”