Is the Fast Diet Healthy?

“Eat, Fast and Live Longer” goes the slogan. The Fast Diet, aka the 5:2 diet, is based on intermittent fasting, which involves eating normally for 5 days per week, while fasting (consuming less than 500 calories (women) and 600 calories (men) for two non-consecutive days per week.

Recent studies report that this isn’t just another fad diet, but has solid footing in science. Well known doctors and health guru’s such as Dr. Mercola and Mark Sisson of Mark’s Daily Apple recommend intermittent fasting for more than just weight loss, but over-all health.

So let’s take a closer look at the claim and surrounding studies and see if they make sense to you.

People in poor countries die of starvation. People in rich countries die of over-eating

The Claim

Too much protein in the diet does not allow proper time for cell repair, leading to diseases such as cancer, heart disease, and diabetes.

The Explanation

Protein causes the body to produce Igf 1, or Insulin growth factor 1. Consumption of protein causes our cells to reproduce, pushing the body to create more Igf 1. Take a bodybuilder for instance, after a workout just about any bodybuilder (that is trying to build muscle) will likely consume a whey protein powder shake. This practice is solely to feed muscles so that they have fuel to grow. Hence, the cells are busy growing/reproducing instead of repairing.

When the cells are constantly busy growing there is no time for repair. It’s like never sleeping. Your cells need time to rest and repair just like the rest of you. This is why children only grow when they sleep, illness lands us in bed (where we often wake up and feel all better). Sleep is when our body can take the time to repair. It’s like trying to fix the freeway when cars are zooming by at 80 mph. Minimal work can be accomplished, and likely the poor repairman who got hired on for the sorry job will get run over in the process!

The body must be given a chance to concentrate on repairing cells instead of reproducing cells

What the Scientific Community Has Found

Restricted vs. All-You-Can-Eat

One group of rats were fed a restricted diet, while the other group had an all you can eat diet. The rats on the restricted diet lived much longer than rats fed an all you can eat diet, as they produced very low levels of Igf 1. Remember, the theory is that the more insulin growth factor 1 swirling through your system, the more likely disease will follow.

Children of the Depression

During the darkest years of the Great Depression (which my grandfather never described as “great”) life expectancy actually ROSE by 6 years! Even the psychology of it all did not affect life expectancy. My grandfather, who survived the Depression by eating potatoes galore, lived to be 94! Although those children of the Depression were full of grit (grits too 🙂 ) and potatoes, they were not full of Igf 1.

The Body Naturally Fasts To Repair

Recently I had a nasty bout with the flu. During that time I had no appetite, and basically did not eat for 4 days. Anything protein related sounded awful. Why? Because my body was in the repair mode. It had no time for nonsense like protein. It wasn’t going to build any muscle, in fact it was likely breaking down muscle to keep the ship afloat (although I was really hoping it would use the fat up first).

Feast or Famine

When our paleolithic ancestors had discovered fire, and were living the good life in cozy caves, do you think they were fortunate enough to bag an antelope, fish, or even a snake on a daily basis? Not year round. Bugs, grubs, roots and tubers, a bit of berries, nuts, or seeds (during the right season) were the main sustenance. A large wild animal was a huge feast, with any excess always being dried, buried, or stored in some fashion for leaner months to come.

The term “feast or famine” has been around a lot longer than the term “3 squares a day.”

Weight loss

The body does very well when you mix things up and surprise it. That’s why we have to rotate workouts, sprint ar do an extra set or two every few days. Our bodies were made to store for future famine. Guess what though? In the United States and many places in the world, that famine never comes! In the meantime we continue to soak up every last calorie, wondering why we can’t control our cravings. It’s because our bodies were not designed that way! The processed food industry has taken full advantage of this very fact by cramming extra calories into every pre-packaged food on the planet. Obesity epidemic? Of course!

Does this mean I should become a vegetarian or vegan?

Any time any dietary extreme is taken, imbalance ensues. I find that the vegan diet often becomes a diet full of the same unhealthy foods in excess. Cheese made out of rice flour and tapioca starch, bread made out of our hybridized flour with soy “butter” to wash it down, nuts in such excess that our Paleolithic ancestors would guffaw at the very notion of using up the entire year’s harvest on one silly “cheesecake.”

I’d rather encourage you to go vegan once or twice a week with a heavy leaning on cooked and fermented vegetables (raw vegetables can be difficult to digest and cause serious side effects for anyone with conditions such as diverticulitis). If vegetarianism is more on your level of “doable” then concentrate those calories on eggs and vegetables, leaving dairy out of the equation for the day.

Is this diet for you?

Who should NOT try this diet

Fasting or severly limiting calorie intake is not for everyone. If you are diabetic, hypoglycemic, or are taking any medication related to blood sugar, heart disease, etc. please check with your doctor before trying this diet. I personally cannot tolerate fasting because of blood sugar instability, so don’t feel like a failure if you can’t fast. It can be very dangerous for many conditions.

This diet might be for you if you:

Are an all or nothing person.

Have a lot of willpower.

Don’t generally have much of an appetite during the day, but then binge at night.

Have a lot of weight to lose, and want to lose it rapidly.

Feel like your body needs some time to detox and regenerate.

Are a male (women can absolutely be successful on this diet, however it seems to work especially well for men).

Don’t have the time or inclination to exercise much.

What to eat when restricted to 500 calories per day


Although, the fast days should consist of a small amount of protein, I’ve found that it’s best for weight loss if you kickstart your metabolism by eating some protein. Try my Low-cal smoothie designed specifically for the fast diet-see video here.

Other options: Whey protein powder (learn how to choose a protein powder and which powders I recommend, here), cottage cheese, chicken breast, and eggs are all low-cal proteins.


My client found that a cup of chili and a glass of iced tea worked well for his lunch (read the entire article about how my client lost 20 lbs in 20 days, here). If you’re doing this more for the cell repair, then I’d recommend a salad with mixed greens, olive oil and balsamic vinegar. Vegetable soup made with chicken broth, and a sprinkle of high quality gelatin (mix in while hot) can be very filling.


My client generally ate a chicken salad for dinner, dressed with olive oil and balsamic vinegar. Sometimes, he just had another shake. If you’d like more of a detox, and are a juicer, then an all vegetable green juice and a cup of chicken broth is a good idea.


Some people survive off of stimulants that are also appetite suppressants such as coffee and tea. Caffeine is a drug and can make your blood sugar run for the hills and then dive off a cliff. I highly recommend that you drink decaf, or if you are addicted to caffeine, then drink green tea with lemon instead. Lemon water is a fabulous liver detox, and will help stabilize blood sugar.

I want to give my cells time to repair but I just can’t fast for 24 hours

Luckily, our body has a built in, wonderful time of fasting all on its own- sleep! Instead of having that midnight snack, or a fill-up right before bed, just quit eating after dinner, or around 7PM. If you don’t eat from 7Pm-7Am that gives the body a full 12 hours to rest, relax, and repair. This is how people ate before the advent of TV dinners and Doritos. People were actually full after dinner! Try it and you’ll be surprised at how quickly the pounds start dropping away.


#MarkSisson #thefastdiet #DrMercola #heartdisease #FastDiet #preventingdisease #cancer #Primal #Paleo #IntermittentFasting #insulin

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