7 Myths Nutritionists Wish You'd Stop Believing

Fact: From celebrities to personal trainers, there's no shortage of so-called experts advocating fasts or juice cleanses to detox. If you Google "detox," you'll get nearly 64 million results for diet programs and treatments that are supposed to help "flush out your system," "remove toxic substances from the body," "give your GI tract a rest," or "speed up your metabolism" and "enhance your overall health." But despite all the hype and popularity, there's little proof that fasting or following a deprivation diet for several days actually delivers on any of the above promises.

While an occasional short fast or a day of following a "juice diet" won't cause harm for most healthy people, it will likely leave you feeling cranky and hungry. If you really want to be and feel your best, eat a healthy diet that includes plenty of fruits and vegetables, get adequate sleep, and don't drink more than one alcoholic beverage per day.

Fact: While you may have read those diet beverages make you gain weight, a recent clinical trial found just the opposite. In the 12-week study, published in the journal Obesity, dieters who drank diet beverages lost 13 pounds on average — 44 percent more than subjects drinking water only, who lost an average of nine pounds. What's more, the diet-soda drinkers reported feeling more satisfied. This study adds to a substantial body of research demonstrating that low-calorie sweeteners and the diet beverages that contain them do not hinder but can in fact help with weight loss. Two peer-reviewed studies published in the American Journal of Clinical Nutrition by researchers from the University of North Carolina in 2012 and 2013 randomly assigned subjects to drink either water or diet beverages (without making any other changes to their diet). After six months, the diet-beverage group had a greater likelihood of reaching a meaningful amount of weight loss — five percent of one's body weight — compared to the control group. These studies reinforce that if you're trying to lose weight, diet beverages may help you peel off pounds, as they can help you achieve and maintain a lower-calorie eating plan.

Fact: Canola oil comes from the crushed seeds of canola plants — not rapeseed plants, which are, in fact, harmful. Rapeseed oil contains high levels of erucic acid, which is linked to heart disease and therefore is not allowed to be sold in the US. While the two plants are cousins, they're distinctly different in their composition. In the 1960s, farmers used breeding methods to help eliminate the erucic acid from canola plants, and canola oil is now regulated to contain negligible amounts of the compound, ensuring that canola oil is 100 percent safe. In fact, it also happens to be one of the healthiest oils (behind olive oil) because it has less saturated fat and more heart-protective omega-3s than other vegetable oils. Canola oil is just seven percent saturated fat compared to olive oil, which is 15 percent saturated fat.

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Fact: Run-of-the-mill Morton table salt and gourmet Himalayan sea salt contain essentially the same amount of sodium per teaspoon — 2,300 milligrams. As for minerals, neither contains enough of any mineral to make it a clear winner over the other. For instance, a teaspoon of table salt has just 1 mg calcium compared to 12 mg in sea salt. Since 12 mg is just one percent of your daily needs, it's not a very healthy way to get calcium into your diet.

Most people believe that sea salt tastes better and, in some cases, you may be able to use less of it (and therefore reduce your sodium intake), but it is by no means a lower-sodium and more mineral-rich option. Keep in mind, sea salt lacks iodine — and not getting enough of this compound can lead to goiter, intellectual impairments, growth retardation, and much more. In fact, iodine deficiency is a serious health threat, especially among pregnant women, according to Boston University researchers, so don't use sea salt exclusively in your diet.

Fact: When something sounds too good to be true, well, it probably is. Take "negative-calorie foods" as an example. The notion is that digesting certain foods burns more calories than those foods provide. The faulty logic of this urban legend is based on the scientifically proven thermic effect of food (TEF), which simply means the amount of energy the body uses to digest a portion of food. The thinking goes, if you were to eat a very low-calorie food — common examples include celery, apples, and limes — then you'd actually create a calorie deficit. In other words, these foods would end up costing less than zero calories.

Sadly, there are no negative-calorie foods. The TEF generally ranges from 10 percent to 20 percent of the calories in a food. So let's say a celery stalk has seven calories. Even if you assume a 20 percent TEF, that means you're still left with about five and a half calories.

Fact: Popular self-help gurus and many diet plans claim that it will take 21 days to form a new healthy habit — or break a bad one. The truth is, there is no magical time frame for breaking bad habits. One study that evaluated behavior change found that creating a new habit, like eating a piece of fruit daily, took an average of 66 days. However, there were wide variations — anywhere from 18 days to 254 days. The authors found the adaptation time was a function of how hard the new behavior is as well as the individual. If you're trying something new, like daily exercise, give yourself time to make it a routine. It may not happen overnight — or even in 21 days!

Fact: You'll often hear someone at the gym say something like, "Since my injury, my muscles have turned to mush." But this isn't the case because muscle and fat tissues are entirely different, and therefore they can never transform from one to the other. It's the equivalent of saying you can turn water into wine or lead into gold.

What really happens when you stop exercising is that your muscle mass declines. And how you gain fat tissue is when you eat more calories than you burn off, which is much easier to do when you're not exercising. And likewise, when you up your exercise routine, you'll add lean tissue and might start burning excess body fat, but your fat didn't turn into muscle.