Mini-Fast May Benefit Overall Health

Mini-Fast May Benefit Overall Health

Ever wish you could trade in your body for a younger model -- like Matthew Perry in 17 Again or actress Jamie Lee Curtis in Freaky Friday…but without the drama? Fascinating science suggests you might be able to by eating “lean and mean” five days a month. The strategy’s not ready for prime time without working with your doc, but it holds promise for protection against cancer, diabetes, heart disease and more.

In a study from the University of Southern California, researchers tested a super-short, periodic, diet strategy that offers the potential benefits of both continual calorie reduction and fasting–without giving up food. Mice ate low-calorie diets for four days twice a month for several months. Humans ate a low-calorie, healthy diet for just five days a month for three months. 

The results? Mice on the eating plan had less cancer, lost more heart-threatening abdominal fat, developed stronger immunity and displayed sharper thinking skills than those who chowed down as usual. They also lived longer. Levels of insulin-like growth factor (IGF-1) -- a compound that can fuel the growth of cancer cells -- decreased. Humans saw improvements in markers linked to a lower risk for cancer, diabetes and heart disease.

In the past, scientists and longevity proponents have experimented with eating reduced-calorie meals every day for years on end. The theory was that it turned on specific genes that increased longevity and dodged disease. The problem? While perpetual calorie restriction may have benefits (it certainly keeps you lean), it’s no fun. Human volunteers wind up feeling tired and irritable -- and their sex drive plummets.

But this “fast-mimicking diet” that combines a five-day low-cal plan followed by regular eating seems to be an effective way to flip on healthy switches throughout your body -- and you never miss a meal.

What five days of low-cal does: In lab studies, the low-cal portion of the plan prompted the death of aging cells and that may increase younger cells' resistance to stress. 

What then eating a normal amount of healthy food does:  Eating normal-size meals again prompts an increase in the number of stem cells  -- the cells that help repair and rebuild tissue throughout the body. That’s quite a one-two punch.

So far the published studies have involved fewer than 40 people, but a larger study involving 70 is underway. It’ll track levels of inflammation and of growth factors like IGF-1 as well as weight, body fat, blood pressure, LDL and HDL cholesterol and levels of important vitamins, minerals and good fats in volunteers’ blood.

Dr. Mike gives it a try: We were so excited about this that after talking with lead researcher Valter Longo, Ph.D., director of USC’s Longevity Institute, Dr. Mike decided to give it a try. At the end of munching mostly veggies for five days (in month one of the experiment), he says he had a slight headache. That cleared up, he felt extra-energetic at the start of his daily exercise routine, then a bit extra-tired toward the end – but not enough to cut it short. The rest of the month, he ate his normal healthy diet based on produce, lean proteins and good fats without food felons like white bread or noodles, added sugars and syrups or other heart threats like red meat and eggs.

We think you should wait to try the fast-mimic diet until Dr. Longo’s larger study is published. If you just can’t, follow these cautions: Check with your doc first. Do not try this on your own, if you have diabetes or follow a special diet for any other reason, if you’re elderly or have chronic health conditions. People on the five-day fast-mimicking phase ate 1090 calories the first day, 725 calories a day after that. And they always got back to eating regularly after five days. Going longer isn’t better. We will check back with Dr. Mike after he gets through his first three months.

Medically reviewed in September 2019.

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