5 Diet Tips You Should Ignore, According to a Registered Dietitian

If you feel like everyone’s a nutrition expert lately, you’re not alone. The sheer amount of diet tips and random nutrition advice online can be overwhelming and confusing, especially because a lot of the time it actually seems to make sense or come with enough anecdotal evidence and testimonials that it starts to feel pretty damn persuasive. The truth is that a lot of this advice is from people who, while eminently qualified to make choices for their own lives and bodies, may (OK, probably) are not qualified to be giving health advice to other people. I know, it’s really frustrating.

Nutrition and weight loss claims are especially ubiquitous, but the good news is that if you know what to look for, you can disregard wide swaths of advice, rather than having to dig deep into the minutiae of every single thing you come across.

I’m here to debunk the biggies for you, so you can never wonder about or fall for them again.

1. This food/supplement/product boosts your metabolism.

I want to get this out of the way first, because it’s the one I see most often. Nothing you consume will boost your metabolism in a substantive way and nothing you consume will burn fat or calories. The only way to burn fat is to burn calories and the only way to do this is a) by living and breathing (most of the calories we burn in a day come from the energy our bodies put into keeping us alive and all our systems working and this is called our basal metabolic rate, b) digesting food, and c) exercise and movement. Ignore diet tips that tell you otherwise.

So-called fat-burning foods (like caffeine and chili peppers) or other products may speed your metabolism a little bit (like, a TINY bit), but they won’t speed it up enough to have meaningful effect on an effort to lose weight or fat. Take chili peppers, which contain a compound called capsaicin. The idea is that the heat from this ingredient spikes your adrenaline, causing your body to crank up the calorie burn. The problem with this theory is that even though it sounds possible, nothing we eat raises our metabolism high enough or for long enough to cause any appreciable weight loss. One small study divided its 25 participants into two groups—people who eat spicy foods regularly and those who do not, and then gave each group a typical serving (about one gram) of hot peppers with lunch. The study found that those subjects who did not eat spicy foods regularly experienced enhanced energy expenditure and reduced appetite. Of course, it could be that subjects decided to stop eating when their mouths started to feel the burn, rather than that the peppers have a magical weight loss property. Indeed, the researchers concluded that the red pepper’s effects seem to be both metabolic and sensory.

Furthermore, the study authors concluded that long term consumption of spicy foods might desensitize people to the sensory effect of hot pepper, so after a while, who knows if those initial benefits would still be possible? But even if the effect remained, the study found that four-and-a-half hours after eating, the subjects who ate red pepper burned 10 more calories than those who did not. So, you know, not much.

Bonus FYI: Drinking ice water doesn’t boost metabolism either, and neither do any other vitamins, minerals, or supplements.

2. You’ll lose X pounds in X time

Do you have a crystal ball that can accurately predict the future? Neither do I. Neither does anyone offering diet advice. That’s why, when someone claims that you’ll lose a specific amount of weight—or even any weight at all—in a certain time frame, you should take that promise with a grain of salt.

We’re all different in terms of genetics, life circumstances, activity levels, and preferences. Those variables make it impossible to project how much weight you’ll lose as a result of an intervention, even if other people (or even if you) have lost weight from that same (or any) intervention in the past. Ignore “pounds you’ll lose” promises, and focus on how healthy and complete an eating plan is. Just as important, pay attention to how it will make you feel. Is it restrictive? Sustainable? Does it teach you how to prepare and portion food? Does it emphasize fresh, whole foods? If something is just for quick weight loss or it seems too good to be true, that’s a big red flag.

3. To be healthy, stop eating legumes/grains/all sugar/a particular food or good group

Sure, there will always be people who can’t tolerate certain foods. Most of us, however, don’t have a problem with the lectins in legumes, the gluten in grains, and the sugar in a reasonable amount of fruit. Cutting those healthy foods out of your diet because someone has scared you into not eating them is unnecessary and unfortunate. The more full-of-whole-foods your diet is, the healthier it is, and the easier it is to maintain. Plus, physical health is one thing, but how about your emotional health? What’s a restrictive diet costing you emotionally? Is it preventing you from living the parts of your life that you enjoy, such as spending meals with friends and family? Is it causing you anxiety and guilt about food and eating? This is also relevant to health and wellness, so if you’re following an eating plan you feel is costing you big emotionally, it’s time to step back.

4. A turmeric latte is a healthier latte

Adding “superfoods” into your life is fine, but they won’t undo or balance out the less healthy aspects of your diet or even make what you eat any “healthier.” So-called superfoods like matcha, turmeric, maca, cacao nibs, and all the others are surely delicious and have their place in a healthy diet, but they don’t have quasi magical properties that aid longevity or optimize your health. So, eat your potato chips fried in coconut oil, but remember: they’re still chips. My point is, when making choices to optimize the healthfulness of your diet, adding in tiny amounts of ingredients, seasonings, and toppings here and there won’t make as much of an impact as, for example, eating less sodium or eating more vegetables. That’s not a reason to not eat that stuff, it’s just a reason to disregard any advice that eating more of it will do something for your health.

5. You can trust my diet advice: I’m a doctor/celebrity trainer/health influencer

It’s sometimes hard to figure out who you can trust for credible nutrition advice. Even though some of us have education, training, and licensing, there are a lot of people out there dispensing advice that’s based solely on their their personal experiences, questionable science, or some combination of the two. Even a credential like an M.D. doesn’t necessarily mean that a person is equipped to tell you, a person who is very much an individual, what will hands down, 100 percent work for you. What’s even more confusing is that there are plenty of people who are conversant enough in the language of health and wellness that they can string together advice that sounds valid, even plausible. But remember, just because someone sounds knowledgeable, it doesn’t mean they actually are, and more importantly it doesn’t mean they’re qualified to be giving out advice. Anyone can Google any health problem, and even spend a significant amount of time researching it, but it’s another thing completely to take on the responsibility—and legality—of diagnosing and counseling other people about their condition and diet. In some cases, misguided advice can be unhelpful or even dangerous.

To wrap it all up, here are a few red flags to watch out for: Anyone using only animal research or very small studies to back up their claims, an “expert” with no formal nutrition training or licensing, anyone who recommends a highly restrictive diet, anyone trying to convince you to try a diet just because it worked for them, and, of course, anyone whose advice involves you buying a thing from them. If you encounter any of this advice, run. Or, at the very least, be highly skeptical and ask a registered dietitian to weigh in on the advice.

Abby Langer has been a Registered Dietitian since 1999. Educated at Dalhousie University in Halifax, Nova Scotia and Loyola University in Chicago, Abby has worked extensively both in clinical nutrition, and nutrition media and consulting. She has won awards for her teaching and has served for three years on her regulatory college’s council. Abby is passionate about all aspects of nutrition, from physiology to teaching to cooking. Her approach to nutrition is permissive and relaxed, and she is a true believer in living your best life without dieting. Abby’s counseling and writings focus on body respect and intuitive-style eating. She has written in depth about debunking fad diets and nutrition myths. Follow her on Twitter and Instagram.