8 weight-loss myths to ditch in the new year, from cutting carbs to doing too much cardio

• There are many weight-loss myths that make losing fat more confusing than it needs to be.
• Spencer Nadolsky, an obesity specialist, and Kara Mockler, a dietitian, debunked the biggest myths.

Weight loss is simple in theory, but not necessarily easy.

With fad diets and so-called experts offering conflicting guidance wherever you look, it can be hard to know what to do if you want to lose weight healthily.

We asked an obesity doctor and a registered dietitian to debunk the biggest weight-loss myths to help give people the best chance of long-term success.

1. Weight loss is all about willpower

Dr. Spencer Nadolsky, an obesity specialist, said that if you're relying only on willpower to lose weight, you're probably not going to be successful.

"Our environments and bodies fight us as we try to lose weight," he said. "It may take some willpower to get started, but to make it longer lasting, you'll have to work on your habits and some may even need medical intervention, like medicine or surgery."

2. You need to cut carbs to lose weight

"This is a common myth perpetuated due to the idea that carbs cause insulin releases in the body and insulin is a fat-storing hormone," Nadolsky said.

Weight loss comes down to being in a sustainable calorie deficit, or eating fewer calories than you burn.

"You can absolutely lose weight while eating carbs despite a release in insulin," Nadolsky said. "There have been meticulous studies looking at this, and it still comes down to a calorie deficit."

3. You need to exercise hard to lose weight

It's understandable that people would think that exercise burns calories and so should lead to greater weight loss — but Nadolsky said it doesn't really work like that, mainly because formal exercise makes up so little of our overall daily calorie burn. He added that expecting it to be what helps you lose a large amount of weight would likely be a letdown.

"It has to do with how our bodies adapt with appetite and other components of our metabolism," Nadolsky said. "We end up losing much less than we should despite a high amount of effort."

But you should still exercise to improve your health and body composition — strength training will help you hold on to muscle while burning fat.

"Do not stop exercising," Nadolsky said. "Change the expectations."

4. Eating at night causes weight gain or prevents weight loss

Kara Mockler, a registered dietitian, told Insider that weight loss comes down to total daily calorie intake; it doesn't matter when you consume the calories.

"If the late-night snacking puts you into a calorie surplus, that's when it hinders weight loss," Mockler said.

5. Fasting makes you lose more weight

People often fast — through daily eating windows or diets such as the 5:2 diet — in a bid to lose weight, but there's nothing superior about it, other than it might help someone stick to a calorie deficit.

"When calorie intake is equated, fasting does not promote more weight loss," Mockler said. "You can spread your total daily calories out however works best for you and still see great results."

6. Cardio is necessary for weight loss

Cardio has many health benefits, but it isn't necessary for weight loss, Mockler said.

"The biggest driver in terms of our weight is how much we eat, and getting that in check is priority one," she said. "Adding cardio into your new healthy routine is like the cherry on top."

7. You have to cut out delicious foods

Losing weight doesn't mean you can never eat the foods you most enjoy.

"Learning how to incorporate your favorite foods into your diet means you're more likely to stick to this way of eating long-term and see better results," Mockler said.

She said that if you put foods such as pizza, cookies, and cake on a pedestal and tell yourself you can't have them, you're more likely to crave them and ultimately overindulge.

"Have small portions of your favorite treats and eat mindfully," Mockler said.

8. Sugar prevents weight loss

Sugar may not be nutritious or particularly satiating (meaning it's easy to overeat), but you don't have to avoid it entirely.

"If our total calories are in check, having a food that contains sugar won't prevent weight loss," Mockler said. "Make sure you're getting enough fiber in your day, and don't feel guilty for having a delicious treat now and then."