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Fasting or Calorie Counting: What's Best for Weight Control?

The best method not only helps you lose but also helps you maintain weight loss.

Key points

  • True weight loss success can only be measured long-term.
  • While many have found that intermittent fasting is an effective means to short-term weight loss, it has not been proven effective over time.
  • A recent study found that limiting total calories is more effective for long-term weight control than limiting the amount of time spent eating.
Kaylah Matthews/Unsplash
Kaylah Matthews/Unsplash

When it comes to weight control, how do you measure success? Fitting comfortably into your clothes again? Liking what you see in the mirror? Feeling fitter?

Those are all good measures in the short term, but the healthiest and most rewarding achievement is the long-term maintenance of a healthy weight once you’re in better shape. Unfortunately, weight maintenance has generally proven to be even more challenging than weight loss.

But now, researchers at Johns Hopkins University Medical Center have determined that some approaches to weight loss yield more successful long-term results than others. Their six-year study, recently published in the Journal of the American Heart Association, found that limiting the number of calories consumed by limiting meal size and meal frequency proved way more successful at long-term weight maintenance than the trendier approach of timed eating, or intermittent fasting.

The Study Design

Study participants included 547 men and women age 18 or older, with an average age of approximately 51 years. The racial breakdown was 79.9 percent White, 12.2 percent Black, 2.9 percent Asian, and 4 percent other/mixed race. Using body mass index (BMI) as a determinant for weight status, the researchers found that 138 participants were at an optimal (healthiest) weight, 169 were deemed overweight, and 240 were classified as obese. Data used in the study was collected from electronic health records, self-reported surveys, and linkage to a mobile app designed by the researchers to record eating and sleeping patterns.

The researchers not only compared the long-term results of intermittent fasting with the long-term results of monitoring meal size and frequency, but they also looked at associations between weight change and time from first to last meal, amount of time from wake-up to first meal, time from last meal to sleep, and total length of sleep. Participants were narrowed down to the 547 who downloaded and consistently used the mobile app. Overall, those who did so were younger and more educated than those who did not download or continue to use the app.

Intermittent Fasting

Intermittent fasting is time-restricted eating that consists of limiting the amount of time between your first and last meal of the day. There are various approaches to intermittent fasting but they are all based on when you eat, rather than on what you eat. So, for instance, the plan could be to eat only between the hours of 10 a.m. and 6 p.m., limiting the amount of time (but not the amount of food you eat) between your first and last meals to eight hours and fasting the rest of the time. If you eat only during those eight hours, you are fasting for the remaining 16 hours of the day and, hopefully, sleeping for seven or eight of those 16 hours. Another approach to intermittent fasting might be to choose two days during the week to limit yourself to just one meal a day of approximately 500 to 600 calories while following a more normal pattern of eating on other days.

The goal of intermittent eating is to give your body enough fasting time to use up all calories consumed during your last meal and then more time to start burning stored fat. It can take up to a month for your body to adjust to this type of eating pattern and for you to be comfortable with it.

As with many alternatives to a normal eating style, intermittent fasting can be difficult to maintain as a lifelong plan and, therefore, any weight loss experienced on this type of diet can also be difficult to maintain. If the idea of intermittent fasting is still appealing, however, it’s important to speak with your doctor to find out if this weight loss plan is healthful and appropriate for you. While intermittent fasting is considered safe for many people, even in the long term for those who can stick to the pattern, this style of eating can come with side effects early on, such as headaches, nausea, and anxiety, and it’s absolutely not recommended for anyone under the age of 18, pregnant or breastfeeding women, those with type 1 diabetes who take insulin or anyone with a history of eating disorders.

Limiting Calories by Limiting Size and Frequency of Meals

Slightly different than the old-fashioned method of counting every calorie in every food item, limiting calories by limiting the size and frequency of your meals may prove to be the most effective known diet plan for maintaining your healthiest weight, according to the results of this research.

The study participants used the specially designed mobile app to record the time they ate and the approximate size of their meals. For the purposes of this study, a large meal consists of more than 1,000 calories; a medium meal provides between 500 and 1,000 calories, and a small meal weighs in at less than 500 calories.

Highlighting Study Results

On average, the final follow-up assessment of each participant occurred about six years after the initial data was collected. The researchers found no association between restricting meals to a limited number of hours and weight change. They did find links between weight change and the size and number of meals consumed.

More frequent large and medium-size meals were associated with weight gain over time, while eating less frequent and smaller meals throughout the day was associated with weight loss and better weight management over a six-year period. The American Heart Association has long recommended limiting total daily calorie intake, choosing healthy foods, and increasing physical activity in order to reduce the risk of cardiovascular disease.

The results of this study support a routine of eating smallish meals throughout the day as a means to long-term weight loss and do not support any type of intermittent fasting. However, the researchers acknowledge that this study does not specifically prove cause and effect, and more studies are needed to confirm their results and determine the best strategies for weight control and healthy weight maintenance. While large-scale, tightly controlled clinical studies are best, they point out that even smaller, short-term studies with consistent results can help determine the very best recommendations for intentional weight loss and healthy weight maintenance in the future.


Zhao D, Guallar E, Woolf TB, et al. Association of eating and sleeping intervals with weight change over time: The Daily24 cohort. Journal of the American Heart Association. February 7, 2023; 12(3).

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