3 dietitians debunk 18 weight loss myths, from cutting carbs to fad diets

• Business Insider asked three registered dietitians to debunk 18 of the most common weight loss myths.
• They explain that you don't need to purge your diet of fat or carbs to lose weight, skipping meals can backfire, and fad diets like the ketogenic diet don't often work.
• Beyond debunking weight loss strategies, they explain that weight loss is not just about discipline. It's about genetics, access to healthy food, and your relationship to food.
• Visit Business Insider's homepage for more stories.

Following is a transcript of the video.

Lorraine Kearney: One of the biggest myths that I get from my clients is that I need to skip meals and starve in order to lose weight. It's not true. So, if you skip meals, it's gonna have such a negative effect on your body that when you do go to sit down and eat, you'll probably overconsume.

Narrator: That's Lorraine Kearney, one of three dietitians we brought into our studios.

Ryan Turner: My name is Ryan Turner.

Nikita Kapur: My name is Nikita Kapur.

Narrator: To debunk 18 of the most common weight-loss myths.

Kearney: The biggest myth that frustrates me the most is that all calories are created equally. A calorie is not just a calorie. It depends on the source of your calories, whether it's coming from caloric-dense foods or nutritional-dense foods. Caloric-dense foods would be more so our cookies, our cakes. We can have a cookie that's 100 calories, we'll eat it, it'll digest really fast, then it's gonna spike our blood sugar levels where, when we start to crash again, we're gonna crave more sugar for that energy pick-me-up.

Narrator: And that can make you gain weight.

Kearney: On the other hand, you can have a banana.

Narrator: Which is an example of a nutritionally dense food.

Kearney: I get the question a lot, do bananas make you fat? Bananas do not make you fat. Bananas, they're a great source of potassium, but for those 100 calories you're also gonna get the fiber and the nutrients that your body needs in that cellular level to make sure that you are healthy and that you're nourished.

Narrator: And you definitely need to nourish your body if you're trying to lose weight.

Kapur: When we are restricting calories, you are restricting the energy source of your body. You're also restricting the energy source of your brain. And if that's happening, then, you know, very primitive, protective mechanisms start to kick into place where your body senses that as a physiological threat and does start to shift your metabolic balance to burn less because it's getting less.

It's kinda like a bad budget. Right? So, if you have a paycheck and you're running out of funds, you're going to conserve how much you pay till your next paycheck. Your body does the same. Your body will jump into this protective physiological, biological mechanism to reduce the amount of energy you're using, which is why it is hard for people to maintain weight.

Narrator: And starving yourself can also shrink your muscles.

Turner: You wanna make sure that you're not eating less than 70% of your overall calorie needs. If you do, that's where not only are you probably gonna feel extremely hungry and it's gonna take you off of any goals that you're setting, but you're probably gonna start compromising your muscle mass as well, and that's where weight loss is gonna be unhealthy.

Narrator: But while the amount of calories you consume matters, the timing might not.

Turner: Timing your meals is always a big question. Everyone comes to me and they kinda smirk and they think that I'm gonna give them a thumbs up when they say, "I don't eat after 6 o'clock or 7 o'clock." And I say, "Oh, all right, do you enjoy that?"

And they say, "No."

And I say, "Well then maybe eating after is OK." Because timing of day is not going to affect weight loss. Calories are what's going to affect weight loss or body-fat loss. So, if you eat a bunch of additional calories and you're in calorie surplus and those are coming late at night, then that's what's causing something like weight gain.

Narrator: And what about eating first thing in the morning?

Kearney: It depends on the body, and it depends on the person and their relationship with food. For a lot of people, me included, if I don't eat a meal, I usually feel very deprived, and it's like I want to make up for it later. If that happens, then that's when we can add in a lot of calories.

Personally, I'm a huge advocate of breakfast. Our body runs on fuel, and food is our fuel. So if we have our breakfast, then we feel we have more sustained energy throughout the day.

Narrator: And if you do choose to eat breakfast, feel free to go for that 2% yogurt.

Turner: Now, fat is incredibly necessary. We should not be afraid of fat. We need fat in the diet. Fat's gonna be necessary for things like absorbing nutrients, like the fat-soluble nutrients like vitamin A and D and E and K. And you also need to make sure that fat, specifically cholesterol, is what's gonna help produce things like your hormones, so things like estrogen and testosterone, growth hormones, so we need all those kind of things.

Narrator: Not only is fat healthy, but fat-free foods are often loaded with sugar or salt.

Kearney: So, if you have a wholesome product and you're removing the fat of it, it's gonna taste completely different. You probably wouldn't even like it. But what they're gonna do is replace that flavor with something else, and usually it's either sodium or sugar.

So, with sugar, when we have, like, a yogurt that has the fruit at the bottom, they're gonna have way more sugars than if you had, like, a 2% Greek yogurt.

Narrator: And, as it turns out, fat isn't the only nutrient you can keep in your diet and still lose weight.

Kearney: One of the biggest myths I get about carbs is that you must omit them from your diet to lose weight, or my body doesn't digest them well and I have to omit them because I'd never lose weight unless I restrict myself. It's not true.

Narrator: And it's just not sustainable.

Kearney: It's almost impossible to have a no-carb diet. Fruits and vegetables are known as carbohydrates, and we must get those for their nutrients. Why carbs have a bad name? It's because of the simple carbs. The carbs that you see prepackaged that are the cookies, the cakes, the sodas, the potato chips.

They're called simple carbs because the chemical structure of them is usually one to two glucose molecules put together. So, when you have, like, a small glucose molecule, it's easy for them to break away.

But with our complex carbs, they are really long chains of carbon that usually are about 18-carbon long, and then, by the time that your body starts to break it down, it's gonna take a while, and that's exactly what we want because it helps balance our blood sugar and also that fiber keeps us full for longer and then also prevents us from snacking.

So, eat your carbs. Definitely eat your carbs and eat your bread. Bread's delicious; it's one of my favorite things.

Narrator: And she has a pro tip for finding bread with more complex carbs.

Kearney: Read your ingredient list. With bread, a lot of those mass-produced breads that are in the bread aisle that are shelf-stable, they can last a month without getting mold on them. And when you look at the ingredient list, it's probably about 50 ingredients long. They're the ones we wanna avoid.

When you're getting bread, get the fresh bread that comes from the local bakery, which is usually around the deli counter area inside of grocery stores. Those will have maybe four or five ingredients, it'll mold after two days, but you can preserve it by just putting it into the freezer and take it out as you need it.

Narrator: And, speaking of bread, what about going gluten-free to lose weight?

Kearney: Gluten-free for weight loss can be a huge marketing ploy. So, with gluten-free, there are a lot of people that do have an intolerance to gluten. Or they have celiac disease, which is where the body starts attacking itself and can deteriorate the body.

Narrator: But there are also people without these conditions who are looking to...

Kearney: Blame something like the gluten without checking the rest of their diet. If you are honest with yourself, recording your food, checking the ingredients, and then you eat the gluten and you feel the intolerance, then great. But a lot of people will choose to just jump in and be like, gluten's the enemy.

Narrator: So, most of us don't need to cut out gluten or fat or carbs to lose weight. But there are some products better left on the shelf.

Kearney: The diet sodas are terrible, with all the added preservatives in them, and the hidden sugars. A lot of the added sugars are the synthetic sugars that are supposed to be great because they don't release insulin, which then doesn't cause a spike in blood sugar levels.

But, internally, if we don't stimulate the release of insulin, those sugars, the synthetic sugars, go to the liver, build up around the liver, hinder the functioning of the liver, and then can lead to nonalcoholic fatty disease. If I'm gonna have a soda, which I have once in a blue moon, it will be the real thing.

Yes, there's more sugar in it, but it's something that I don't have on a regular basis.

Narrator: Better yet, she says, drink water.

Kearney: Jazz up your water. Add fruit to it, add some mint or cucumber, lemon. Yes, it'll take a little bit for your taste buds to reset, but you're getting so many nutrients from that water, and your body requires water for it to function optimally.

Water is one of the six nutrients that the body needs. And when we're dehydrated, it also mimics the signs of hunger. So people turn to food a lot if they're dehydrated, not realizing that they're not hungry, it's just your body saying, "Give me some water, I'm thirsty."

Narrator: And what about juice?

Kearney: Oh, juice cleanses. [laughs]

So, juice cleanses are, like, one of my pet peeves. If you're having a juice every once in a while, great. You're still getting the antioxidants out of it, you're still getting the nutrients, but you're removing that fiber. And fiber is key for the body to support gut health.

With a lot of juice cleanses, they're hella expensive, and we have this belief that they're gonna be better for our bodies or it's a cleansing effect of our body. Realistically, what's happening is that, when you have those juice cleanses that are mostly coming from, like, fruit sugars and then the vegetable sugars, it's a high, high amount of fructose in the body.

When the body consumes excess fructose, it has a spasming effect of the GI tract that can lend to the cleansing effect. So that when we are actually having a reaction to the high amounts of fructose in the body, people think it's the cleansing effect because the marketing ploys have led us to believe that way. But it's not.

You would be better cleansing your body by actually eating the apple, eating the spinach, and eating all the other fruits that are in that cleanse. That would be better for you because fiber is our natural detox. What it does is it goes through the body, picks up, like, excess fat, metabolic waste, and help cleanse it out.

Narrator: But juice cleanses aren't the only diet fads that don't often work.

Turner: Intermittently fasting is probably a question I get all the time. It's...we can kinda put it in that myth category.

Narrator: Now, it can restrict calories and, at least temporarily, help you lose weight.

Turner: If you're only allowed to eat food for eight hours, that just gives someone a lot of structure, and that can be very, very helpful. You can only get so many calories in your mouth in that time. On the flip side, someone can get a lot of calories in their mouth during that time as well.

So, someone can, and I've seen many people do it, they've gained weight through intermittent fasting. So it's not just gonna be this quick fix; there's nothing magical to it.

Narrator: And the same goes for many popular diets.

Kapur: So, one of the common diets right now that is gaining popularity is the ketogenic diet. So, a lot of people who are doing that are just eliminating carbohydrates, which is why that's hard to sustain, because your body does need carbohydrates for a reason.

To be honest, there's not a lot of research that's saying that that is something that is helpful. There's maybe a lot of research in mice models, but that hasn't been transcribed into human studies.

Narrator: And while people have lost weight on keto, it's often not without side effects.

Kapur: They're eliminating whole grains and legumes, certain fruits and vegetables, and really increasing their fat intake, which, although fats are important, excess of any nutrient can cause metabolic changes in your body that will impact your cardiovascular health, your physical health, your metabolic health.

So, an example would be patients that we're seeing in the clinical setting are following ketogenic diets, are seeing weight loss, however, are coming with higher cholesterol markers, they're coming with higher LDL markers, they're coming with more irritable bowel symptoms, they're coming with more gastrointestinal discomfort.

Narrator: The truth is there's no one tool that will make you magically lose weight.

Kapur: I think the most prevalent concept around health these days is biohacking, which is this idea that you can defeat biology, you can work around your genetic predispositions, your metabolic parameters, and that is actually not true. And the reason for that is because you cannot defeat biology, you cannot hack hunger, you cannot hack access to healthcare, you cannot hack motivation.

And this idea that, again, if those results are there, you're going to be able to feel more satisfied is also not true. So, this biohacking works on this concept and this belief that, you know, you can work your way and fix your body, and that prescribes to the social construct that it is up to you to change that.

Narrator: And that's also why most diets don't work.

Kapur: They're hard to sustain, they're hard to maintain, so the results are very temporary, which is why we go back to something, trying something new. It's important to focus on behaviors rather than outcomes.

Kearney: Where you should start is record your food. A simple food log to lose weight is really just being honest with yourself, identifying your foods and the hidden ingredients that could be contributing to excess of hundreds and hundreds of calories per day.

Take olive oil. Olive oil is great. But when we cook with it, we usually free-pour it into a pan. Each tablespoon of olive oil has 128 calories. Now, if you're pouring in, like, 6, 7, 8 tablespoons with your vegetables, you're getting almost 1,000 calories that you don't need.

Narrator: So, pro tip for cooking with olive oil:

Kearney: Put it in, wait till your pan is hot, once it's hot, add 1 to 2 tablespoons of olive oil, and then add in your vegetables. When the pan is hot enough, it will disperse easier and then you'll use less. Also, once you put the vegetables in, some water and moisture will come from those vegetables and will add to the liquid in the pan, so you actually don't need to add excess in.

Narrator: And if you are being mindful of what you eat, that whole idea of cheating? Kearney isn't a fan.

Kearney: I don't think there is any cheat meals. I don't like the word cheat. I think it gives it this, it gives us this, like, higher power, like, oh, this is really bad and I can't believe I did this, I completely fell off the wagon.

No, remove that. Because then you're gonna want it more, you're gonna feel even more guilty about it. If you go out and you're socializing and you're trying out one of New York's best restaurants that's filled with cream and butter, enjoy it. Just try to get a salad to start.

And filling up on salad is a great way to cut the calories, and then, have, like, one of the appetizers that are not in line with your health goals with your table and share, 'cause sharing is caring.

Narrator: And there's more good news.

Kearney: You can still lose weight while drinking occasional alcohol, if you're sticking to the cleaner foods. And by omitting all the foods that you tend to enjoy in the past, by omitting alcohol, trying to increase your exercise, and then doing this, like, detox fad all in one goal, it's overwhelming, and it's setting you up for failure.

So doing it in stages and being more realistic about what you can change now, and then work towards it. What I usually recommend to my clients is take care of your food now. You'll understand how your body feels when it's nourished, understand how your gut health is supposed to be supported, and then we'll focus on alcohol and working in the exercise.

Narrator: But the thing is, no matter how much we care about it, weight definitely isn't everything.

Kapur: I think one of the biggest myths around weight loss and weight is that overweight equals unhealthy, normal weight equals healthy, as defined by the BMI category.

BMI is a very inaccurate measure of health because it is just looking at your height and weight without taking into account what your metabolic factors and parameters are, what is your physiological health, your physical health, your sleep, your mental health, your relationship to food.

And I think it's very important to factor those things if we really wanna define someone as healthy. And if we're not gonna look at it more holistically, I think what that does is it marginalizes people in bigger bodies.

Narrator: Plus, not everyone can lose weight, even if they're putting in the same effort.

Kapur: That's a very common myth, that everybody should have, has the same ability to lose weight, and if everybody eats the same way, they're gonna look the same way, which is very untrue, and that's incorrect. And the reason for that is I think it's important to understand that someone's weight is a factor of so many different things.

It is so complex. All the way from your genetic predispositions, your family history, your past medical history, your relationship to food as you were growing up, because not everybody has access to food.

Because health is about inclusion, access, connection, joy, physiological well-being, and we have to take those factors into account.