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Intermittent Fasting Doesn’t Have Long-Term Effects on Weight Loss

— February 24, 2023

Fasting isn’t as effective as calorie counting, research shows.

A new study published on in mid-January in the Journal of the American Heart Association revealed that the common “fad” diet practice of intermittent fasting is in fact not effective for weight loss over time. While immediate results may be noticeable, they’re not sustainable. The research team at John Hopkins University found that when trying to lose weight, the amount of food a person eats is much more important than the time of each meal. The study consisted of 547 individuals, all of whom were asked to record both the size of their meals and the timing of when they ate on a mobile app daily over the course of six months. The scientists then recorded the participant’s weight over the course of roughly six years, five years before they began logging their meals, and roughly six months after, using electronic health records.

Within the study, the participant’s meals were divided into three distinct size categories: meals with fewer than 500 calories, meals that ranged from 500 to 1,000 calories, and meals consisting of over 1,000 calories. The results of the study demonstrated that those who ate the most large and medium meals gained weight over six years, and those who ate smaller, fewer meals lost weight.

Intermittent Fasting Doesn't Have Long-Term Effects on Weight Loss
Photo by Andrea Piacquadio from Pexels

These results are consistent with the long-standing belief that keeping your eating within a calorie deficit is what contributes to weight loss. There was no link found in the study between weight change and limiting food intake into a specific time window, which is the practice referred to as intermittent fasting. They also found no relation between weight change and the timing of a person’s first or last meal of the day.

The study accounted for several variables, and its participants included people of various weights, including overweight and severely obese individuals. The weight changes that were observed in the study were fairly small overall, but people who ate an extra daily meal saw less than 1 pound of weight gain per year, on average, relative to those who did not eat the extra meal.

Researchers who worked on the study say that the results provide evidence that restricting meal size can be effective for weight loss, even after adjusting for baseline weights. They also noted that on average, people will gain 1 or 2 pounds a year, which can amount to significant weight gain over time.

However, other research has found that the timing of meals can matter. A study that was published in October 2022 reported eating earlier in the day may contribute to weight loss, perhaps due to an increased feeling of fullness throughout the day, or because it helps people burn calories because they’re more likely to move about during the daytime.

Another factor worth considering is the nutritional value of the foods people consume, and that the quality of a person’s diet is also a large determinant in weight gain or loss. If someone consumes a large amount of highly processed food, for instance, it can lead to weight gain. On the opposite end, having a diet that consists of lots of organic foods can help with losing those extra pounds. All in all, the value of one’s food intake is likely more important to weight management than the time of day in which intake occurs.


Intermittent fasting wasn’t associated with weight loss over 6 years, a new study found

Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates

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