Fasting to lose weight and live longer may not be the panacea that wellness gurus might want you to believe.
A study just found that when it comes to dieting, the best way to add years to your life may be to simply reduce your daily calories.
The study in mice found that mice who reduced daily calories by 20 to 40 percent lived on average a third longer than mice who ate what they wanted.
So in humans, if you’re someone who eats 2,500 calories a day, that would be the equivalent of cutting out a bagel with cream cheese or two avocados.
Mice that ate fewer calories overall also fared better than mice that fasted for a day or two at a time, suggesting that regular timing of eating is beneficial to health.
To calculate your daily calorie needs, scroll to the bottom of this article.
Time-restricted eating has been a popular technique in fitness and diet circles for decades. But this study suggests it may have fewer longevity benefits in mice than just eating a regular schedule with fewer calories overall
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Dr. Gary Churchill, Karl Gunnar Johansson chairman and professor at the Jackson Laboratory who led the study, told DailyMail.com that the mice that were put on a low-calorie diet for a long time without losing much body weight lived the longest.
This means that not only does your diet play a role in your lifespan, but so does your genetics.
‘The most robust animals maintain their weight even under stress and calorie restriction, and they are the ones that live the longest,’ said Dr Churchill.
Researchers have known since the 1930s that restricting calories in the laboratory can help animals live longer.
In humans, having a healthy body weight can help control blood pressure and cholesterol, reducing the chance of developing conditions such as diabetes, heart disease and cancer, all of which lead to a shorter lifespan. according to Mayo Clinic.
For some people, this means reducing the amount of food they eat in order to gain or lose weight.
Still, Dr. Churchill said, there is much debate about the best way to do this, and how fewer calories will affect the body at the cellular level.
So he and fellow scientists at the Jackson Laboratory—an independent research group specializing in genetics research—began investigating the topic almost a decade ago. Their results have just been published in the magazine Nature.
They divided nearly 100 mice into five different diets and monitored them throughout their lives to see what happened to their health.
In the first group, the animals could eat as much food as they wanted, whenever. In the second time, the mice received 60 percent of their basic calories. In the third, the mice received 80 percent of their base calories.
In the fourth period, the mice fasted for a day and then ate whatever they wanted for the rest of the week. In the fifth period, the mice fasted for two days and then ate whatever they wanted for the rest of the week.
The average lifespan of the mice that ate without restriction was 25 months. Those who fasted lived for 28 months.
Those who ate 80 percent of their basic needs lived 30 months – 20 percent longer than the group without restrictions. Finally, those who ate 60 percent of their basic needs lived an average of 34 months – 36 percent longer than the group without restrictions.
Dr. Churchill noted: ‘we extended lifespan with these extreme interventions, but they also had some serious drawbacks.’ The calorie-restricted mice were cold, hungry and showed signs of a weaker immune system – and were thus more likely to get sick than the unrestricted mice.
“These diets are extreme,” he told DM.com. Therefore, it should not be something that people consider adopting for themselves.
The five diets included one that was unrestricted, two that included fasting and two that included calorie restriction. The calorie-restricted diets showed the greatest increase in lifespan
It’s important to keep your weight and blood sugar levels stable, he said. But instead of thinking about restricting your calories to that extent, he said, focus on eating a balanced diet and consider eating a little less if you want to lose some weight.
Metabolic calculators, which use your body weight, age, height and activity level, can help someone get an idea of how many calories he or she needs to adjust to lose weight.
Interestingly enough, Dr. Churchill said, not all mice within the calorie-restricted groups did the same. Some lived very short lives, while others lived as long as four years.
The difference between these groups is that those who lived the longest were able to maintain a relatively stable weight. So it wasn’t as simple as the fact that restricting calories helped the mice lose weight and were therefore healthier.
Instead, it suggests that what may be more important than weight or calories is how resilient your body is to stress.
This also has to do with your genes, said Dr. Churchill. These probably have a greater impact on your lifespan than your diet. ‘If your grandmother has lived to be over 90, you have no influence on that. But if she did, that’s a bonus,” he said.
Other factors, such as avoiding sunscreen and tobacco, also play a role. When it comes to diet, he said, keep this in mind as one of many factors that can extend your lifestyle. Simply put, he said: ‘pay attention to your health.’