The 5:2 Fast Diet: Dieting for Health and Anti-Aging
The 5:2 Diet (also written as 5+2) is an eating plan based on the concept of Intermittent Fasting (IF). As the name implies, IF alternates higher calorie days with lower calorie days, the theory being that these caloric swings trigger the body to produce an abundance of beneficial chemicals. Because the chemicals that are released are thought to forestall medical disorders often associated with aging such as adult onset diabetes and dementia, IF has been touted for years as an anti-aging diet.
The 5:2 uses the basic principles of IF - high and low calories days - but adds a bit more structure in order to make the diet plan easier to follow. In this article I'll walk you through the basics.
The 5:2 Diet: How it works
The 5:2 Diet is one of the simplest eating plans to follow that I've come across. No food lists, no points, no exercise requirements. Simply choose two days in your week to be your "fast days" and on these days only, restrict your total calories to 500 for women, 600 for men. The rest of the week eat whatever you'd like. That's basically it!
A couple of finer points:
- The fast days can be done over any 24-hour time period. So instead of a traditional day, you can distribute your 500/600 calories from noon to noon or 6 PM to 6 PM or whatever works best for your schedule. For example, you could have a regular breakfast and lunch (say done by 12:30), followed by a light dinner and a light breakfast the next morning, then back to a regular lunch (after 12:30 the next day).
- Dr. Michael Mosley, pioneer of the 5:2 and author of The Fast Diet, recommends that the two fast days not be done back-to-back. They should be separated by at least a day, presumably to prevent the body from going into hunger mode from prolonged calorie reductions.
The 5:2 Diet: Does it work?
The two main benefits touted by IF are improved health and weight loss. Let's examine the medical evidence for each.
Improved health: Most of the formal medical studies on IF are based on animal testing, which are't necessarily conclusive for humans. A study by the National Institute of Aging reportedly linked IF with lower levels of IGF-1, a biomarker associated with Alzheimer's and Parkinson's diseases, but the results are difficult to assess. Other agencies, such as the UK's National Health Service, outright dismiss health benefits of IF and strongly suggest the diet be avoided.
Formal medical studies aside, however, there's plenty of anecdotal evidence - personal testimonies and informal studies - that suggest the 5+2 can help lower the risk of cancer and heart disease, and increase overall energy. Dr. Mosley tracked his cholesterol and blood sugar levels while following the 5:2, and measured significant decreases in both after only just nine weeks.
Weight loss: This one's a bit tricky. If you keep your calories on the non-fast days to "normal" levels - approximately 2000 for women and 2400 for men - you will lose weight. The math is simple: your weekly calorie deficit from IF is about 3000 for women, 3600 for men. Since every 3500 calories saved equates to one pound of weight loss, this means that men can expect to drop about a pound a week, women slightly less (about 85% of a pound, or about 6 pounds every 7 weeks).
Adding just a bit of light exercise can help speed up the weight loss. For instance a moderately-paced 30 minute walk burns about 100 calories. Doing this three times per week will bump female dieters just about to the one pound/week mark.
On the other hand, overeating on the non-fast days can slow your weight loss down to nothing. You'll still get the health benefits and the anti-aging boost, but your waistline won't budge.
The 5:2 Diet: Survival Tips
The 5:2 Diet is one of the easiest plans to follow, but there are things you can do to make it even easier.
- Don't feel like you have to pick the same two fast days each week. Look over your schedule for the week ahead and choose the two days that make the most sense. Just make sure to leave a 24-block of non-fast time in between.
- Drink plenty of water on fast days - 8-10 glasses - to stave off both hunger and dehydration. Clear broth, miso soup, and coffee/tea can also help, but be sure to include the calories.
- It might take a few trials to come up with a fast day calorie distribution that works for your body. Some prefer to eat a light breakfast (~200 calories) and a light dinner, and skip lunch altogether. Others eat a mid-afternoon lunch and skip dinner. What works for me personally, is a 100 calorie breakfast, 150 calorie lunch, 100 calorie afternoon snack, and a 250 calorie dinner. I also reserve about 10 calories for sipping on chicken or veggie broth after work.
- Focus on veggies and lean protein on your fast days to feel fuller and sustain your energy. A couple of low-cal cookies might fit the calories requirements, but could swing you toward an energy low. I like veggie-egg white frittata, veggie soups (made with broth, not milk or cream), and salads with tuna, ham, salmon, etc. They feel like a full meal but at much lower calories.