top of page

The surprising reason a sugary diet could stall weight loss

Updated: Apr 11

image showing colorful donuts floating on lavender background.
Reducing sugar intake is a healthy lifestyle habit with numerous benefits

It’s not all that surprising that ice cream and cookies have more calories than, say, carrots, but the harmful effects of sugar on the body go far beyond calories. A sugary diet influences how well (or not) you sleep. And inadequate sleep can have a significant impact on your weight. Therefore, if weight loss is your goal, getting the recommended amount of sleep is crucial. And if you’re struggling with your sleep, you may benefit from reducing your sugar intake.

How sugar influences your sleep

Numerous studies tie a healthy diet with better sleep. For instance, 2016 research found that a typical American eating pattern high in sugar and saturated fat (in red meat and full-fat dairy foods) but low in fiber (found in plant foods) was associated with more nighttime wakings and less time spent in deep sleep. That’s the kind of sleep you need for your body to heal and function optimally.

A 2022 study added to this evidence, showing that those with the highest sugar intake had the poorest sleep quality, which was better among people with lower sugar diets. In fact, people who consumed the highest amount of added sugar were 3.5 times more likely to have sleep problems compared to those with the lowest intakes.

Meanwhile, eating well may have the reverse effect, helping to improve sleep. For example, a 2020 study found that people who ate more fruits and vegetables reported better sleep. So did people who ate legumes. And, those who adhered to a Mediterranean diet fell asleep faster, had fewer nighttime arousals, and experienced better overall sleep quality. (To fast track better sleep, here’s how to get started on a plant-based diet, and here are some easy vegetable side dishes.)

How inadequate sleep stalls weight loss

  1. It might make you eat more sugar. Yup, read that again! A 2018 study involved counseling chronically sleep-deprived people on the importance of extra sleep. Those who got the counseling session slept more, and even though they didn’t meet the recommended amount of sleep or receive diet advice, they lowered their added sugar intake by 10 grams per day. That’s equal to 2 ½ teaspoons, which is the amount of sugar in a Halloween-size candy bar. So, just to clarify, by sleeping more, these folks naturally curtailed their added sugar intake.

  2. It may intensify your cravings. When you skimp on sleep, it alters the way you view sweets and other unhealthy foods, making them more irresistible. That could make you feel more vulnerable in the presence of certain foods, which could lead to overeating. (Here are healthy sweet snacks to satisfy your cravings.)

  3. It makes the decision to eat less healthfully easier. If you’re attempting to eat well, choosing something unhealthy can prompt an internal debate as you weigh whether or not to go for it. A 2021 study measured this used eye-tracking movements to assess how conflicted people felt when choosing specific foods. After a night of restricted sleep, people felt less conflicted choosing unhealthy fare, so lack of sleep made that choice feel easier.

  4. It promotes overeating. It comes down to the fact that short-changing your sleep alters your appetite-regulating hormones in a way that makes you hungrier and delays the feeling of fulness. One study showed that people served themselves a bigger lunch with 12.4% more calories after getting a third less sleep one night. (If you tend to overindulge, read what to do after a cheat day.)

Another study looked at whether getting more sleep could help, and it turned out that it can. People who typically slept under 6 ½ hours per night were counseled to get more sleep. They then extended their sleep by about 1.2 hours per night. What happened next? They cut 270 calories from their daily diet without dietary counseling or attempting to restrict what they ate. The researchers concluded that if they kept up the healthy sleep habits, it could translate to a 26-pound weight loss over three years.

Healthy sleep habits

Besides making a point to go to bed at night (vs. scrolling on your phone or binge-watching TV), here are some things you can do to sleep better.

  • Stay within reasonable added sugar limits. The recommended limits are 6 teaspoons per day for women and 9 teaspoons per day for men. Here are some pointers for lowering your added sugar intake.

  • Don’t eat too close to bedtime. A late meal or snack can trigger reflux, which disrupts your sleep. It’s ideal to close the kitchen at least a couple of hours before you go to bed. Here are tips for managing late-night snacks.

  • Reduce your caffeine intake. Some people are extra sensitive to caffeine, and even a morning cup of coffee can keep them up at night. However, for most of us, it takes about five hours for caffeine to leave the body, so beware of caffeine after mid-afternoon.

  • Watch your booze. It might help you doze off, but if you drink more than a drink (women) or two (men) per day, it can undermine the deep, restful sleep you need.

  • Get some activity. Walk, practice yoga, run, hike, spin. Do what you like, but do it often because it’ll help you sleep.

  • Use tools to relax. Your brain and body might need some extra help winding down. Consider tools like journaling and meditation.

  • Prime your body and mind for sleep. The ideal bedroom environment is cool, dark, and quiet. It’s also a good idea to park the electronics away from the bed, so you aren’t tempted to pick them up and start scrolling. Finally, make sure you wake up at the same time most days.


Weight loss is complicated, and it involves more than what you eat. A sugary diet can contribute to excess calories, but it can also undermine your sleep, and if you aren’t sleeping well, it could interfere with your progress. Practicing better sleep habits is a healthy lifestyle change that can significantly impact your appetite and the way you think about food, which may help produce the calorie deficit needed to lose weight. (Here are my top weight loss secrets.)

bottom of page