Fasting to lose weight and live longer might not be the silver bullet that wellness gurus may have you believe.
A study just revealed that when it comes to diets, the best way to add years to your life may simple to be reducing your daily calories.
The research, done on mice, found those that 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 eating 2,500 calories per day, that would be the equivalent of cutting out a bagel with cream cheese or two avocados.
Mice that ate less calories overall also fared better than mice who fasted for a day or two at time, which suggests that regular timing of eating is beneficial to health.
To calculate your daily needed calories, scroll to the bottom of this article.
Time restricted eating has been a popular technique in fitness and dieting circles for decades. But this study suggests it has less longevity benefit than just eating a normal schedule with less calories overall, in mice
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Dr Gary Churchill, Karl Gunnar Johansson Chair and professor at Jackson Laboratory who led the study, told DailyMail.com that the mice who were put on a low calorie diet for a long period of time without losing much body weight lived the longest.
This means that it’s not just your diet that’s playing a role in your longevity – but also your genetics.
‘The most robust animals keep their weight on even in the face of stress and caloric restriction, and they are the ones that live the longest,’ Dr Churchill said.
Researchers have known since at least the 1930’s that restricting calories in the lab can help animals live longer.
In humans, having a healthy body weight can help keep blood pressure and cholesterol in check – decreasing the likelihood of developing conditions like diabetes, heart disease and cancer, all which lead to a shorter lifespan, according to Mayo Clinic.
For some people, this involves tapering the amount of food they eat in order to gain or lose weight.
Still, Dr Churchill said, the best way to do this, and what affect less calories has on the body at a cellular level, is widely debated.
So he and fellow scientists at the Jackson Laboratory – an independent research group that specializes in genetic research – began looking into this topic nearly a decade ago. Their results were just published in the journal Nature.
They sorted nearly 100 mice into five different diets, and watched them over their lifespan 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, the mice were given 60 percent of their baseline calories. In the third, the mice were given 80 percent of their baseline calories.
In the fourth, the mice fasted for one day and then eat whatever they wanted the rest of the week. In the fifth, the mice fasted for two days and then eat whatever they wanted for the rest of the week.
The average lifespan for the mice who ate unrestricted was 25 months. Those who fasted lived 28 months.
Those who ate 80 percent of their baseline lived 30 months – 20 percent longer than the unrestricted group. Finally, those who ate 60 percent of their baseline lived on average 34 months – 36 percent longer than the unrestricted group.
Dr Churchill noted: ‘we extended lifespan with these extreme interventions, but they also had some serious downsides.’ The calorie restricted mice were cold, hungry and showed signs of a weaker immune system – so were more likely to get sick than the unrestricted mice.
‘These diets, they’re extreme,’ he told DM.com. It therefore shouldn’t be something humans consider adopting for themselves.
The five diets included one that was unrestricted, two that included fasting and two that included calorie restriction. The calorie restrictive diets showed the greatest increase in longevity
It is important to keep your weight and blood sugar stable, he said. But instead of thinking about restricting to your calories to such a degree, he said, you can focus on eating a balanced diet and consider eating slightly less if you’re looking to lose a little weight.
Metabolic rate calculators, which use your body weight, age, height and activity level, can help give someone an idea of the amount of calories they may have to tweak in order to lose weight.
Interestingly, Dr Churchill said, not all mice within the calorie restricting groups fared the same. Some lived very short lives – while others lives as long as four years.
The difference between these groups is that the ones 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 their weight and therefore they were healthier.
Instead, it suggests that what might be more important than weight or calories is how resilient your body is to stress.
This also has to do with your genes, Dr Churchill said. These probably have a greater affect on your lifespan than your diet. ‘If your grandmother lived past 90, that’s not in your control. But if she did, that’s a bonus,’ he said.
Other factors, like avoiding sunburns and tobacco, also play a role. When it comes to diet, he said, keep it in mind as one of many factors that may extend your lifestyle. Put simply, he said: ‘pay attention to your health.’
