By Corrie Pikul


They're not only ineffective in the long term, but they often have unexpected health consequences.


The Week of Magical Fasting: Diets Made Up of Just One (Very Healthy) Thing

juice diet


The method: For several days in a row, you eat nothing but the one food (cabbage soup, grapefruit), food group (raw vegetables and fruit) or type of food (juice).


The promise: You'll drop pounds fast, kick-starting a long-term healthy-eating plan; you'll reset your metabolism; you'll clear out the "toxins," fats and other nasty things that are glomming you up.


The problem: When you eat only one kind of food, you fail to eat all the other kinds, so you miss out on protein, fats, fiber and other essential vitamins and nutrients.


The risks: After a few days, your calorie-starved body may break down muscle mass for energy. This can throw off your metabolism and make future calories (i.e., the ones you'll consume after the fast) harder to burn off. Consuming massive quantities of the foods that make up these diets—vegetables, fruit—can lead to uncomfortable bloating as well as severe diarrhea[1] . Further, what are leaving your body aren't "toxins" (your body naturally flushes out excess nutrients, as well as chemical substances) but the effluvia of an out-of-whack gastrointestinal system that's both overloaded with water, simple carbs[2] and fructose, and deprived of solid matter.


What's more, says Lisa Sasson, a registered dietician and a clinical associate professor of nutrition and food studies at New York University, for those who already have an unstable relationship with food, this kind of fasting usually leads to obsessive thoughts. ("At the end of this juice rainbow is a nice, rare steak. And curly fries.") Let's be clear: No nutritionist is going to rip a beet-apple tonic, cup of veggie soup or kale salad out of your hands. But most would also agree that a week's worth of these foods (in the absence of any others) is an impractical way to lose weight. (By the way, if you really want to "cleanse," Sasson suggests eating more whole grains and high-fiber foods, which act like a natural scrub brush to clear out the intestines.)


The Diet with the Backwards Ratios: High Protein, Low Carb

atkins diet


The method: Eat protein[3] , and lots of it. Also known as: Bring on the double bison burgers[4] (without the bun).


The promise: You'll burn more calories by digesting protein, and, because protein takes a while to leave your stomach, you also feel fuller longer.


The problem: By consuming 30 to 50 percent of your calories in bacon, eggs or even tofu, you won't get the carbohydrates[5] you need. Yes, carbs are often maligned for their almost addictive pull and simple white carbs have been linked to weight gain, diabetes, inflammation and heart disease. But this food group remains the most efficient fuel source for the body, explains Sasson (who is, by the way, a fan of lean protein). Carbs are crucial for tissues and organs like the brain and the heart. If you don't supply your body with adequate amounts of carbohydrates, it's forced to use energy from muscle as well as fat.


The risks: Breaking down too much muscle and fat for fuel can lead to the production of ketones, which can cause nausea, bad breath, headaches, muscle soreness and, over time, kidney stones, gout and even kidney failure. Other potential unpleasant side effects include constipation (from a fiber deficit), intense fatigue and weak bones (animal protein can increase blood acidity, leading your body to use its calcium to neutralize it). So even though high-protein, low-carb diets are preferred by some fitness buffs, the American Heart Association specifically advises against them.



The Strategy That Claims to Lengthen Your Life as It Shrinks Your Body: Calorie Restriction
woman diet plate[6] [7]


The method: Eating 20-to-25 percent fewer calories than your body needs to function. (Using the FDA's general recommendation of 2,000 daily calories[8] , a person on this type of diet would consume only 1,500 to 1,600.)


The promise: You can lower the risk of your getting heart disease and improve your cardiovascular function—all while slimming down.


The problem: When you drastically cut calories, your body adapts by learning how to do more with less. It lowers your metabolic rate, holds on desperately to fat stores and takes longer to execute basic functions like breathing; it literally slows down to survive, says Sasson. There's a hotly debated theory that this adaptive response also slows the aging process. But, while initial research on the link between cutting calories and adding years seemed encouraging[9] , the latest studies are much less convincing. (For now, the jury is still out[10] .)


The risks: Eating just a little bit more than your strict low-calorie usual (say, during a stressful business trip) makes you more likely to put on pounds—and, worse, it's tougher to get rid of them. You're also at a higher risk of losing muscle and bone mass (and testosterone, if you're male). And unless you're following this eating plan under the close supervision of a doctor, Sasson says, you will likely end up deficient in essential nutrients.




Loading Slideshow...



  • They OD On The EVOO


    <strong>The rationale:</strong> "Olive oil is so good for me -- I can never have too much of it."

    <strong>The mistake:</strong> Actually, you can, say registered dieticians Tammy Lakatos Shames and Lyssie Lakatos, aka <a href="http://nutritiontwins.com/" target="_hplink">the Nutrition Twins</a>. They find that many of their health-conscious clients think the health benefits of this Mediterranean oil (e.g., <a href="http://www.oprah.com/health/Nutrition-Facts-About-Olive-Oil-Health-Advice-from-Dr-Katz" target="_hplink">heart-healthy monounsaturated fats, flavonoid antioxidants and vitamin E</a> ) cancel out its calories. But it's still an oil -- one that packs 120 calories and 14 grams of fat per tablespoon. "People will put 300 calories in the pan before they even start cooking," the Nutrition Twins tell us.

    <strong>Try this: </strong>Measure out the oil you use for cooking as well as for dressings or sauces. The Nutrition Twins also suggest putting olive oil in a spray bottle so that a little will go a longer way.




  • They Avoid Fruit Like It's Candy


    <strong>The rationale: </strong>"Fruit is loaded with sugar that will cause me to pack on the pounds."

    <strong>The mistake: </strong>While "nature's sweets," especially the variety that grows on trees, do have a high percentage of naturally occurring sugar, fresh fruit comes with benefits like essential vitamins, minerals and fiber, which can help you feel fuller longer, says <a href="http://rebeccascritchfield.com/" target="_hplink">Rebecca Scritchfield</a>, a Washington, DC, registered dietitian and fitness expert. That's why some weight loss plans (<a href="http://www.weightwatchers.com/util/art/index_art.aspx?tabnum=1&art_id=108831&sc=3002" target="_hplink">like Weight Watchers</a>) consider fruit a "freebie" and encourage people to eat it without guilt . Fruit that has been pulverized into juice, on the other hand, is lacking in filling fiber, and bottled juice often contains added sugar.

    <strong>Try this:</strong> Scritchfield recommends 2 to 3 pieces of whole fruit (1 cup of blueberries, raspberries or sliced strawberries) per day. Another sweet point in fruit's favor: The anthocyanins in a fiber-filled cup of <a href="http://www.blueberrycouncil.org/health-benefits-of-blueberries/blueberry-nutrition/" target="_hplink">blueberries</a> or <a href="http://circ.ahajournals.org/content/127/2/188.full.pdf+html" target="_hplink">strawberries</a> are associated with lower cardiovascular risks and improved cognition.




  • They Go Gluten-Free (For No Good Reason)


    <strong>The rationale: </strong>"I've heard that some people feel less bloated when they give up gluten."

    <strong>The mistake: </strong>Those who suffer from wheat-related bloat may have Celiac disease, an autoimmune disorder in which wheat damages the small intestine --<a href="http://www.celiaccentral.org/celiac-disease/facts-and-figures/" target="_hplink">but it affects less than one percent of Americans</a> (the less-severe <a href="http://www.runnersworld.com/nutrition-for-runners/are-you-really-gluten-sensitive" target="_hplink">gluten insensitivity is also less common</a> than most people realize). The gluten warning is specifically intended for those diagnosed with one of these conditions, but the Nutrition Twins see many people using it like a weight loss plan. These misguided dieters avoid all forms of gluten -- including satisfying, heart-healthy whole grains -- and, worse, swap food made from wheat flour for food made with processed rice, corn or soy flour. These commercial products can also be high in sugar and sodium, making them more unhealthy than the food they're intended to replace.

    <strong>Try this: </strong>The 2010 Dietary Guidelines for Americans recommends that <em>everyone</em> <a href="http://www.cnpp.usda.gov/Publications/DietaryGuidelines/2010/PolicyDoc/ExecSumm.pdf" target="_hplink">switch from refined grains to whole grains</a>. Even those diagnosed with a gluten sensitivity can still enjoy <a href="http://www.celiaccentral.org/Gluten-Free-Food/the-gluten-free-diet/" target="_hplink">naturally gluten-free grains like amaranth, buckwheat, flax, millet, quinoa and teff</a>.




  • They Eat Way Less And Exercise Way More


    <strong>The rationale:</strong> "When I was in college, I dropped 10 pounds in two weeks by living on fat-free yogurt and running 5 miles every day."

    <strong>The mistake: </strong>"When you drastically cut calories, you're telling your body to lower your metabolism and slow down weight loss," says Scritchfield. The problem is that your appetite may not easily adjust to your new restricted eating plan. So even if you drop pounds in the short term, you risk gaining them back -- plus extra -- as soon as you give in to satisfying your cravings.

    <strong>Try this: </strong>While <a href="http://www.choosemyplate.gov/weight-management-calories/calories.html" target="_hplink">2,000 calories per day is the average target for most Americans</a>, <a href="http://caloriecount.about.com/tools/calories-burned" target="_hplink">this calculator</a> or <a href="http://www.choosemyplate.gov/supertracker-tools/supertracker.html" target="_hplink">this tool</a> can help you find the bull's-eye for your age, weight and activity level.




  • They Think It's Crazy To Eat Nuts


    <strong>The rationale:</strong> "Nuts are basically little fat pills."

    <strong>The mistake:</strong> "I have a lot of clients who are still afraid to eat nuts," says <a href="http://www.nutritiouslife.com/" target="_hplink">nutritionist Keri Glassman</a> -- despite all the news about their high ratio of "good fats." Glassman reminds nut-o-phobes that fat is not only an essential nutrient, but it can also help them lose weight by filling them up and helping to satisfy cravings. One study found that <a href="http://www.ift.org/newsroom/news-releases/2013/july/16/the-right-snack-may-aid-satiety.aspx" target="_hplink">participants who regularly snacked on almonds ate less for the rest of the day</a>.

    <strong>Try this: </strong>Choose almonds over less-nutrient-dense pretzels or fatty potato chips. Just be mindful of portion size: Glassman recommends a palmful of peanuts, almonds or cashews or two tablespoons of the spreadable stuff. If you're worried about overdoing it, stick with pistachios in the shell, because research has shown that <a href="http://www.oprah.com/blogs/The-Pistachio-Nut-Mind-Trick" target="_hplink">shells serve as cues that signal us to stop snacking</a>.