1. Fat-free food leads to fat-free bodiesIn the 1980s, new dietary recommendations everyone to adopt low-fat diets. Only recently has it become clear what a mistake that was. Dr. Michael Alderman said low-fat diets might have helped spur the national rise in obesity and diabetes.
We now know that fats are necessary for health. Fat is critical for the optimum functioning of the brain, the heart, the skin and other major organs, as well as for the absorption of many vitamins.
They are also good for dieting. Fat digestion suppresses ghrelin, the hormone that makes us feel hungry, while simultaneously spurring the release of peptides that make us feel full, found a study published in the American Journal of Physiology, Endocrinology and Metabolism in 2005.
2. Energy bars will power weight lossPower Bars, Zone Bars, MetRx and so on are all processed foods. And processed foods, almost to a rule, can sabotage even the most committed diet in part because they are so easy for our bodies to absorb.
Think of processed foods as partially-digested foods. They allow our guts to laze about, conserve energy and encourage weight gain.
While most scientists, including Wrangham, do not recommend a diet completely composed of raw food, avoiding processed foods, even ones with aggressive health claims, will help you reach a healthy weight, Lippert said.
3. Grazing will boost metabolism and help you lose weightWhile going too long without eating can set you up for diet catastrophes, "grazing can also rack up calories," Lippert said. Handful after handful of almonds, or continuous sips of banana-soy smoothies, will eventually appear on your waistline, she said.
A grazing habit degrades a person's internal guidance about when to eat, making it nearly impossible to tap into hunger and satiety cues, Lippert said. "If you can't remember the last time you were really hungry, that is not a good thing," she said.
4. Saturated fat causes cellulite, and it's bad for you anywayCellulite is no different than other body fat; some fat just gets stored as cellulite in some parts of the body. And any excess body fat is caused by excess calories, no matter whether those calories come from bacon, donuts or carrot sticks.
Past studies lumped saturated fat in with trans fat, giving the former a bad rap by association. But while trans fat is truly evil, saturated fat found mostly in animal products performs many critical functions, such as helping the body use calcium and omega 3s, boosting the immune system and protecting major organs from disease.
5. You can eat whatever you want, as long as you exerciseExercise is not a very effective way to lose weight, researchers say. The amount of exercise needed to lose even a single pound -- if diet is not rethought -- is more than most people can do, Apovian said.
If you are just exercising, the scale is unlikely to budge, agreed obesity researcher Susan Carnell of Columbia University. "You can make a better impact by controlling what you eat."
But don't give up your exercise routine. In addition to a host of general health benefits, including protecting your brain, heart and bones, exercise is great for maintaining weight and regulating appetite, Carnell said. In fact, a daily habit of intensive exercise is the shared trait among once-overweight people who successfully stay slim, Apovian said.
6. Beer gives you a bellyAlcohol, however, may be in a separate class, as far as liquid calories go.
At 7 calories per gram, alcohol is what scientists call a "non-trivial" calorie source. (A gram of fat has 9 calories, while protein and carbs, including simple sugars, have 4 calories per gram.) So imagine their surprise when, in a 13-year study of 19,220 U.S. women, teetotalers were more likely to become overweight than women who regularly imbibed beer, wine or liquor.
The link remained even after accounting for a slew of lifestyle factors, including exercise habits, nutritional intake and smoking status. "We are quite confident that the association we observed is due to the biological effect of alcohol," lead researcher Dr. Lu Wang of Harvard Medical School told LiveScience.
7. Juice detoxes, smoothies and diet sodas are effective weight-loss toolsIn our hunter-gatherer days, "we didn't have a lot of liquids with calories, explains Dr. Caroline Apovian. As a result, our bodies today interpret beverages as having fewer calories than they actually do and find them less satisfying than solid food and so we eat more to compensate.
Many scientists think non-diet beverage consumption -- those with sugar -- contributes to excess weight gain. And while often villainized, sodas are not the only culprits. Juices, smoothies and various "health drinks" can also confuse our internal calorie-counters and make weight difficult to control.
What about diet drinks? People who regularly slurp artificial sweeteners are more likely to gain weight, according to a study published in the journal Obesity in 2008. The most touted explanation for this finding is that fake sweeteners increase cravings for calorie-dense foods, but the science behind this theory is mixed. Still, if you want to play it safe while tightening your belt, stick to water.