If you want to see me grit my teeth, ask me about a cleanse — a one-week kick-start to a whole-new-better-you simply by subsisting on a “proven” blend of herbs, juices, and whatnot. Even better, proclaim that you’re doing a cleanse — and that it’s worth every penny you paid to an online guru, your local personal trainer who’s “a nutrition expert,” or the celeb author with a picture of a puke-green shake on his or her book cover.

BEWARE. Because they’re hailed as a quick fix to rid your body of toxins (sounds great, right?), lose weight and cure just about every ailment imaginable, cleanses are all the rage. As it turns out, they’re not a new phenomenon: the lemon juice/maple syrup/cayenne pepper cleanse, commonly referred to as the “Master Cleanse,” was popular in the 1940s, long before our fast-food revolution and bloated midsections began to appear. Are cleanses new? No. Are they a big business? Yes. A cure-all? Heck, no!

Let’s start with the toxins that cleanses are purported to rid from your body. WHICH TOXINS? As a scientist, I want to know. And how come we don’t flush these toxins like we do other toxic substances in our bodies — like ammonia, for example, which is a byproduct of protein metabolism? Ammonia is toxic to the brain in high concentrations, so the liver and kidneys do this amazing thing — they help clear the body of it, through our urine.

Cleanses also promise quick weight loss. Well, yes: restricting your intake to a funky concoction of juice and spices, or only pulverized vegetables, for 10 days will lead to temporary weight loss. It’s simple math — and simply unsustainable. And it’s not nutritious. By completely ignoring several food groups, you’ll be depriving your body of many essential nutrients. (Well, some cleanse adherents say, “take a supplement while you’re on this cleanse to ensure nutrient balance.” What? If you’re cleansing your body, why would you take a PILL?) You’ll also be starving yourself, which results in your body SLOWING down its metabolism — the last thing you want to do if you’re trying to lose weight. When people come off a cleanse, which they always do, and resume a normal American diet, which they almost always do, most gain back all the weight they lost — and then some. Finally, if you’re devoid of calories and low on energy during a cleanse, how do you exercise?

In fact, exercise is a key part of reducing your body’s quotient of THE great toxins, excess sugar, salt and saturated fat, which raise your risk of excess inflammation and chronic — and life-threatening — diseases, not to mention back pain. Exercise boosts metabolism, burns fat and calories, and moderates your blood sugar levels. So you want to get rid of toxins? Great. Don’t put too much alcohol, caffeine, processed foods, or alternative sweeteners in your body in the first place. And then exercise — and let your liver and kidneys do their job too.

But if you must cleanse, try my “vegetable, fruit, and exercise cleanse.” It includes skipping all processed and packaged food items, which are loaded with added sugar and bad fats (trans and saturated)…along with minimizing caffeine and alcohol and banning pastries and chips, which we could all use a little less of. Load up on wholesome foods, including lean protein and some whole grains, with a major focus on colorful nutrient-dense fruits and vegetables which are of course “all natural” and loaded with anti-inflammatory compounds. They are also packed with fiber, which has a funny little way of cleaning you out. And then exercise daily, moderately to vigorously, if possible. Try it. It WORKS.

Dr. Jennifer Sacheck

Dr. Jennifer Sacheck is an Associate Professor of Nutrition at the Friedman School of Nutrition Science and Policy at Tufts University and also holds an appointment in the School of Medicine. She is both a nutrition scientist and exercise physiologist by training with over two decades of experience working with athletes and non-athletes alike on the benefits of physical activity and optimal nutrition both for health and performance. Her research has spanned laboratory studies on muscle damage, growth and recovery to studies in the greater public community where she translates the latest science on food and nutrients into real world applicability. Dr. Sacheck has served on multiple national committees, including the Institute of Medicine and the American College of Sports Medicine where she is also a fellow, and recently co-authored her first book with Chris Crowley on fitness and health, “Thinner This Year.” Dr. Sacheck received her PhD from Tufts University and completed her post-doctoral training at Harvard Medical School. Learn more about Dr. Sacheck here.