The column is a good reminder of 1) why the solution to shedding unwanted pounds cannot be found in a single food or pill (sorry), and 2) why we need to ignore the ridiculous claims made by companies hawking weight-loss and other supplements.
I’ve written here before about how the multibillion-dollar supplement industry, thanks to a few powerful congressional friends, is essentially shielded from any meaningful government regulation. The makers of supplements are free to make general health claims about their products without first undergoing a federal review to determine if those claims are true.
And they do. Shamelessly. Woolston provides several examples, including the website claims by the makers of one popular weight-loss supplement that its product “increases the metabolic mechanism in your body.”
“The site also says the green tea and caffeine [in the product] will ‘rev up your metabolism’ and ‘increase energy, focus and physical performance,’ ” writes Woolston. “The site features testimonials it says are from users who claim they have lost huge amounts of weight. … One man says he dropped more than 100 pounds, although it’s unclear how long that took. A woman says she lost 40 pounds in less than a year, including 20 pounds in her first month.”
But such claims and inferences are not backed up with good science — or any science. Writes Woolston:
Caffeine shows up in a lot of weight-loss products, but it doesn’t seem to be any sort of silver bullet against flab, says C. Michael White, a professor of pharmacy at the University of Connecticut in Storrs. White says that, to his knowledge, there are no well-designed studies showing that caffeine works better than a placebo when it comes to weight loss.
White notes that caffeine is a diuretic, which means that people taking large doses might shed some weight through water loss, but that’s not the kind of slimming most users are looking for.
As reported in a 2010 issue of the International Journal of Obesity, caffeine may in fact be able to increase a person’s metabolic rate by 4% or 5%. But, according to White, there’s no clear evidence that this translates into actual weight loss. …
Caffeine does seem to enhance the weight-loss powers of some other ingredients, White says. For example, green tea contains antioxidants that encourage cells to burn extra calories, and caffeinated green tea seems to promote more weight loss than decaf versions. But even this combination yields very modest results. “In clinical trials, the weight loss is 2.5 to 4 pounds, not 40 pounds,” White says.
In fact, a 2004 randomized, placebo-controlled study in the British Journal of Nutrition found that green tea had absolutely no effect on weight loss. Furthermore, although Woolston doesn’t bring it up in his column, some research suggests that caffeine may hinder weight loss by interfering with your body’s sensitivity to insulin and by raising your cortisol levels, both of which may lead to weight gain. Caffeine, of course, also wreaks havoc with sleep, and studies have found that lack of sleep alters hormones in ways that may increase your hunger and make you feel less full after eating.