Intermittent fasting has become one of the most popular approaches to weight loss in recent years. Many people choose this eating style because it is simple and does not require counting calories every day.
Instead, people focus on when they eat. Some limit their meals to a certain number of hours each day, while others eat normally on most days and significantly reduce calories on a few days each week.
Two of the most common forms of intermittent fasting are time-restricted eating and the 5:2 diet. Time-restricted eating usually involves consuming all meals within an eight-hour window and fasting during the remaining sixteen hours.
The 5:2 diet involves eating normally for five days each week and cutting calorie intake substantially on the other two days.
Many studies have shown that intermittent fasting can help people lose weight. However, scientists have long wondered whether everyone responds to fasting in the same way. A new analysis suggests the answer is no.
Researchers reviewed 28 clinical trials involving more than 1,800 adults. Their goal was to examine how intermittent fasting affects people of different ages and whether age influences health outcomes beyond weight loss. The findings were published in the journal Nutrients.
The researchers found that intermittent fasting reduced body weight and body mass index across different age groups and in both men and women. This confirms that fasting can be an effective tool for weight management regardless of age.
However, the study also revealed that the body’s response to fasting is more complicated than many people realize. While younger and older adults both lost weight, the changes happening inside their bodies were often different. According to the researchers, age appears to influence how metabolism adapts to fasting.
One of the most important findings involved muscle loss. Many people assume that weight loss mainly comes from body fat. Unfortunately, that is not always true. When people lose weight, some of the loss often comes from muscle tissue.
Previous research has shown that around 20% to 30% of weight lost during dieting may come from muscle. In one fasting study reviewed by the researchers, as much as 65% of the weight loss came from lean tissue rather than fat. This finding is concerning because muscle plays a vital role in strength, balance, mobility, and healthy aging.
Muscle loss may be particularly problematic for older adults. As people age, they naturally lose muscle mass over time. Losing additional muscle through dieting could increase the risk of weakness, falls, reduced independence, and poorer overall health.
The good news is that the review identified ways to reduce this risk. Several studies found that combining intermittent fasting with exercise helped preserve muscle while still promoting fat loss. Resistance training, such as lifting weights or using resistance bands, appeared especially beneficial.
Higher protein intake also played an important role. Protein provides the building blocks muscles need to maintain and repair themselves. Researchers suggest that people practicing intermittent fasting should pay close attention to protein intake, particularly older adults.
Another surprising finding involved cholesterol levels. Intermittent fasting is often promoted as a way to improve heart health, and many studies have reported reductions in LDL cholesterol, sometimes called “bad” cholesterol. However, this review found that LDL cholesterol tended to increase slightly across many age groups.
This unexpected result does not mean intermittent fasting is harmful. However, it suggests that people should not assume all health markers will automatically improve. The researchers recommend regular cholesterol testing for individuals who follow fasting diets for extended periods.
Overall, the study paints a more balanced picture of intermittent fasting. The approach can help people lose weight, but the effects go beyond the number on the scale. Age, exercise habits, protein intake, and individual biology all influence the final results.
The researchers conclude that intermittent fasting should be viewed as a useful tool rather than a universal solution. People who choose this eating pattern may achieve the best results by combining fasting with strength training, eating enough protein, and monitoring key health markers such as cholesterol.
If you care about weight loss, please read studies that hop extract could reduce belly fat in overweight people, and early time-restricted eating could help lose weight .
For more health information, please see recent studies about a simple path to weight loss, and results showing a non-invasive treatment for obesity and diabetes.
Source: University of Córdoba.
