By David H. Rahm, M.D.

Q: Over the past 20 years I’ve gained 15 pounds and I’d like to lose it. I’ve heard that the Fast Diet is not only effective for weight loss but weight maintenance. Is this just the latest fad diet or does the Fast Diet really work?

You’re not alone in having gained a pound or so a year in adulthood, struggled with shedding the weight and fought with keeping the pounds off. From Weight Watchers to Atkins, there are no shortage of diet plans to choose from. The question is which one works best for you and how to keep the weight off long-term. For many, the Fast Diet seems to work on both levels.

What is the Fast Diet?

The Fast Diet, also referred to as the “5:2 diet” was introduced last summer in Britain. Since then, the diet has gained considerable attention both abroad and in the states.

The book is available on Amazon for less than $12.00 however delivery can take upwards of 3 weeks as it ships from the U.K. For faster delivery, consider downloading to the Kindle for around $10.00.

The diet was introduced by Michael Mosley, M.D. a doctor who for the last 25 years has made numerous science and history documentaries for the BBC. In early 2012, Mosley was approached by the editor of the BBC series Horizon to do a segment on life extension. Dr. Mosley quickly focused on intermittent fasting and used himself as the guinea for testing out the concept.

While there are many forms of intermittent fasting (eating fewer calories but only part of the time), Dr. Mosley focused on a “5:2” approach whereby on 2 days of the week he restricted his daily intake to 600 calories and on the remaining 5 days, he ate what he wanted. This approach allows dieters to eat the foods they enjoy most of the time.

The program, Eat, Fast, Live Longer chronicled the doctor’s adventures while on the Fast Diet. The story was viewed by millions and picked up by newspapers around the world.

Eat, Fast, Live Longer – Watch the Video on PBS

Why the 5:2 Approach?

Whether for religious, weight loss, health or other reasons, a number of fasting approaches are followed by many people around the world. Two of the more common forms of fasting include:

Caloric Restriction (CR) reduces your intake of calories to a level 20-40% lower than is typical, while still obtaining all the necessary nutrients and vitamins.

Alternative Day Fasting (ADF) is a specific form of intermittent fasting that alternates between periods of fasting and non-fasting.

Dr. Mosley experimented with different forms of fasting but came up with eating fewer calories on just two days a week. He found that the so-called “5:2 plan” not only conferred similar health benefits as CR or ADF but was more doable and allowed for a long-term commitment to a dietary plan.

One of the problems of just about every diet is not that dieters don’t lose weight but they gain it all back and sometimes even more. A key advantage to the Fast Diet is that the diet plan is rational, sustainable, flexible and feasible for the long haul.

What’s the Science Behind Intermittent Fasting?

A number of studies on intermittent fasting have been done in animals and in humans.

Studies done on mice have shown that caloric restriction increased their life span compared to a group of mice with a normal diet. The calorie-restricted mice also maintained youthful appearances and activity levels longer and showed delays in age-related diseases.

NPR Podcast: Two-Day Diets: How Mini Fasts Can Help Maximize Weight Loss

Studies done on rhesus monkeys showed that caloric restriction blunts aging and significantly delays the onset of age-related disorders such as cancer, diabetes, cardiovascular disease, and brain atrophy.

Human research has shown that intermittent diets are a safe, viable alternative approach to weight loss and maintaining a lower weight in comparison to daily dieting.

What are the Health Benefits of Intermittent Fasting?

Not surprisingly, a key benefit of intermittent fasting is weight loss but other health benefits accrue using this dietary plan:

Lose Weight While Preserving Muscle. Unlike many restricted calorie diets, intermittent fasting leads to steady and sustainable weight loss but does not cause muscle loss.

Protection Against Chronic Disease. In human studies, dieters on intermittent fasts saw improvement in key numbers including body mass index (BMI), total cholesterol, LDL or “bad” cholesterol, triglycerides and fasting glucose. As a result, they reduced their risk for chronic disease particularly cardiovascular, obesity and type 2 diabetes.

How to do a Juice Cleansing Fast

Protection Against Aging. Evidence supports that periodic fasting can induce long-lasting changes that are beneficial against aging. A number that improves with intermittent fasting is IGF-1 (Insulin-Like Growth Factor 1). Higher levels of this cellular stimulant later in life lead to accelerated aging and cancer. Periodic fasting reduces the amount of IGF-1 the body produces and switches on repair genes. With intermittent fasting, you fool your body into thinking that it’s in a potential famine situation and it switches from “go-go” mode to maintenance mode.

According to Mosley, our bodies are designed to fast. We respond well to intermittent fasting because it mimics more closely than 3 to 5 meals a day the environment in which humans were shaped.

Brain Health Benefits. Another benefit of intermittent fasting is enhancement of mood and sense of well-being due to increased production of neurotrophic factor. Studies in mice indicate that intermittent fasting is beneficial for learning and memory. Research suggests that periodic fasting increases production of a protein called brain-derived neurotrophic factor (BDNF). In rodent studies, rising levels of BDNF have an anti-depressant effect.

Other Benefits of Intermittent Fasting

You might be surprised to learn that while you’re engaging in periodic fasting, it’s easier than you think, you won’t starve to death and you’ll still be able to concentrate.

Some other benefits of periodic fasting that you may not be aware of:

• You’ll have more energy
• You’ll sleep better and upon awakening will be more alert
• Your skin will look better

From an eating perspective, periodic fasting will teach you:

• feelings of hunger and fullness
• portion control and how much you really need to be satiated
• to be more aware of your eating on days you don’t fast and likely result in your eating less on days following the fast

Practical Advice & Examples

In the book, Dr. Mosley provides guidelines and tips on how to go about doing a fast. For the two fast days, menu plans for women (500 calories a day) and for men (600 calories a day) are provided along with a calorie counter for a wide range of vegetables, fruits, grains, protein, dairy, sauces/dips/dressings, drinks, desserts and snacks.

Weight Loss vs. Weight Maintenance (INFOGRAPHIC)

The book also includes a section of a wide range of individuals and their firsthand account on what it was like to embark on the Fast Diet.

A Good Plan for You?

Based on the research and judging from many dieters who have been on the program, The Fast Diet represents a good solution for those struggling to lose weight and keep the weight off.

I’m certainly accustomed to fasting – my wife and I usually do a three day juice fast once or twice a year. Last year, my wife switched to fasting one day a week for about a year. More recently, she tried the Fast Diet for 8 weeks and found it to be the easiest plan for losing a few pounds. In addition to reducing her BMI, I suspect that her blood levels have improved further. She will be getting these measured in the next month.

If the Fast Diet sounds appealing, you should first consult with your doctor before embarking on the plan. Also, certain individuals such as pregnant women, those with eating disorders and Type 1 diabetics are advised against using this type of dietary approach.