Why yo-yo dieting is making you gain body fat

... and why you probably want to avoid calorie and carb cycling diets.

Who hasn’t been part of the “Diet Starts Monday Crowd?”

Or have you tried following a “weight-loss program” that tells you to have super low-calorie days and feast / refeed days on the weekends? And wonder why it only “worked” the first time?

Well, here’s why.

Spending the majority of your week in a caloric deficit causes metabolic adaptations to Resting Energy Expenditure, regardless of “maintenance” days or mini “maintenance breaks.”

When you zoom out, you’re still in a calorie deficit most days, and your body adapts accordingly.

Even worse, when we spend prolonged periods of time in a caloric deficit OR lose a significant amount of body weight quickly (<15%), the body has a strong preference for disproportionately storing any excess energy into body fat via a process called collateral fattening (PMID: 29559726).

This phenomenon is not observed in shorter, more sustainable deficits.

So let’s break this down:

What Is Calorie Cycling?

To level set the terminology here, let’s define calorie cycling, or what some of you probably know as yo-yo dieting, aka the 6-week challenge from an influencer.

For the sake of this post, this is where you have severely low-calorie days the majority of the week, and are a couple hundred calories above maintenance the rest of the week.

This is either done intentionally via some pretty awful nutrition programs out there, or the “diet starts Monday” crowd.

Or where you don’t love how you feel after a weekend out and then drastically drop calories on the weekdays so low that it’s unsustainable. Then a boomerang in hunger occurs on the weekends.

Rinse and repeat.

What Does Eating at Maintenance look like?

Eating at maintenance is when your range of caloric intake matches your energy expenditure, and your body weight stays the same.

In this example, this person’s maintenance calorie range is 2300-2500, matching their expenditure.

What does calorie/carb cycling look like?

What if that same person restricts calories during the week to overeat on the weekends?

At first, they may lose some weight. The example below shows eating 1500 calories four days per week and 2800 on the weekends, averaging 2100 calories, creating a 200-500 calorie deficit.

Adapted Maintenance

Because they’re technically eating in a deficit, their maintenance adapts to lower values over time.

Now, this person is averaging the same calories as when they started the program and gaining weight. The high-calorie days create a surplus, and the body stores incremental body fat on those days.

A Better Fat loss phase

In a sustainable fat loss phase, you set a moderate and manageable calorie range for the deficit that doesn’t create boomerang hunger cues that cause weekends to be off the rails.

You plan it for a specific time period that you can get in and out of. Adaptations still occur, but you can manage them.

How do I fix it?

So you realize you’re the person who diets Monday-Friday and YOLOs every weekend?

And you see the scale creep and feel helpless?

Now is the time to actually eat at maintenance for once—not a few days a week, but every day.

By consistently eating at maintenance, you are no longer in a low energy availability state, and your body no longer needs to store every excess calorie.

Only then will it start to reverse metabolic adaptation.

Rather than eating lower calories during the week, start eating at your calculated maintenance calories every day. You won’t want to eat more on the weekends because you’re actually feeling fed and fueled.

How do you find your maintenance calories? Don’t worry, we have a guide for that here!