Keith Kantor, Ph.D. Nutritional Science, NAMED Program
The 5:2 diet has slowly crept across the pond to North America and it is gaining momentum. The idea was first presented in an hour-long documentary on the BBC called "Eat, Fast, Live Longer" aired during the Summer, 2012 Olympics. Michael Mosley, the narrator and guinea pig for several different fasting diets, thought no one would even notice it.
Well, he was wrong! This diet, a type of intermittent fasting, has taken Britain by storm, and newspapers frequently publish recipes for devoted followers. Mosley is a trained doctor but has spent the better part of his career covering medical topics for the BBC. He was 53 at the time of filming. At 5 foot, 11 inches and 187 pounds he did not feel that he was unhealthy. Shockingly his doctor had told him he was pre-diabetic, and an MRI revealed he had a significant amount of internal body fat. He was thin on the outside and fat on the inside (TOFI), which put him at a higher risk for a multitude of health problems.
This led Mosley on a quest to get healthy, reduce his risk of diabetes and cancer, and lose some of the internal fat surrounding his vital organs. After meeting with many researchers, he ended up settling on the 5:2 diet plan.
What Is the 5:2 Diet?
The 5:2 diet is a form of intermittent fasting, where calories are unrestricted five days a week and restricted the other two.
- Women eat 500 calories two days a week and 2,000 calories the other five days.
- Men eat 600 calories two days a week and 2,400 calories the other five days.
How Much Weight Can I Lose on the 5:2 Diet?
The 5:2 diet has been shown to burn only fat, roughly one pound a week.
Nutritionists at the University of Illinois reported in a 2013 study that participants in a 12-week alternating feeding/fasting day diet lost a little more than 11 pounds in 12 weeks.
How Does the Diet Work?
- It is not necessary to count calories during the five "feed" days. Just be aware that you are staying roughly within the range of 2,000 or 2,400. Pay attention to hunger cues and the feeling of satiety.
- Try and ensure that the two "fast" days chosen are not consecutive days, or by the 48th hour you may be tempted to eat your right arm! The days can vary week to week depending on your schedule.
- Try to get in lean protein every couple of hours throughout the day. This means including lean protein in all your meals and eating protein snacks during the day. Fat and carbohydrates can be stored in the body as fat, but protein cannot be stored.
- You want to eat smaller meals, frequently, in order to keep your blood sugars from plummeting and your metabolism revved up. Also, your body can only handle so many calories at one time (what it doesn’t use for energy it will store as fat mass).
- Choose carbohydrates that are high in fiber and low in added sugars. Watch your saturated fat intake.
- Make sure to drink plenty of calorie-free drinks on fast days, preferably water, tea, or coffee. Try not to consume diet sodas, as the effect of aspartame can play with insulin production. Stevia is fine in moderation because it is all natural.
- The calories on fast days can be consumed over the course of the day, although Mosley prefers splitting them between breakfast and dinner, leaving 12 hours in between. Some research for the alternate day fast shows people eating all of the calories in one sitting around lunch. Mosley’s co-author Mimi split them into three small meals and still lost weight.
Who Shouldn't Do This Diet?
- Anyone who is pregnant or breastfeeding.
- Any Type 1 diabetic and most Type 2 diabetics, because fasting can lead to hypoglycemia in these people. Check with your doctor first. Research has shown improvements in insulin resistance with intermittent fasting, but since diabetics have individual and isolated lab values and symptoms, they should let their provider know what they are doing.
- Anyone with a history of eating disorders or at high-risk of developing an eating disorder. Counting calories can be a trigger for an eating disorder relapse or development.
- Underweight people.
Can I Lose Weight Safely With Intermittent Fasting?
Nutritionists recommend this type of diet for people who can't seem to lose weight no matter how healthy their food and portion sizes.
"This could be a hormone reset that would benefit them and break their weight loss plateau," says Keith Kantor, a doctor of nutritional science and naturopathic doctor in Atlanta. "This type of diet is a fantastic option for certain individual lifestyles. It is a great diet for those who feel like they are eating healthy, portion-controlled meals but are struggling to lose weight."
Kantor adds that this diet may feel rigid at first and does not need to be followed exactly right away. Those who may be intimidated can ease their way into the protocol over the course of days or weeks. This will be less overwhelming and more likely to create long-term success.
A Typical Fasting Day
Here are some suggested fasting day menus:
- Eat two eggs and a slice of ham for breakfast (300 calories).
- Drink water, tea, coffee, and calorie-free drinks until dinner 12 hours later.
- Dinner then can be a 300 calorie meal for men, 200 for women: a chicken breast is 150 calories, paired with a mountain of vegetables or a broth-based soup.
- Eat 200 calorie oatmeal with blueberries for breakfast (200 calories).
- An apple for lunch (80 calories).
- A 200 calorie dinner: half a chicken breast and stir-fry veggies or broth-based soup.
- Calorie-free drinks all day.
- Protein shake for breakfast (120 calories).
- Salad for lunch: 2 cups arugula, 4 tablespoons cucumber and red pepper, 10 grape tomatoes, 1 tablespoon sweet onion, 1 tablespoon lemon-garlic vinaigrette (77 calories).
- 300 calorie dinner.
- Calorie-free drinks all day.
Tips to Make the 5:2 Diet Work
- Get creative with your calorie-free drinks. Buy a selection of flavored, caffeine-free teas. They can be brewed hot or served over ice. Sweeten with stevia if desired. Try and drink before you develop hunger pangs and the day will go much more smoothly.
- Get to know the calorie count of food items. Read labels. Download an app! It is shocking how low in calories veggies are, so vegetables will likely make up a good part of your fast day menu. Prepared meals are fine too. The label will have the calorie total, doing the work for you.
- Plan out fast days before they happen. Make sure you have the food on hand. I don’t like to cook on these days, but I do have a family to feed, so I often make soups in the slow cooker.
- My favorite tip is to make or buy good-quality soup. For my serving, I add equal parts chicken stock (usually around 7 calories a cup). This ends up cutting the calories in half. For instance, a soup that is 200 calories a cup becomes 103 calories a cup once diluted with stock. This allows you to fill up on two cups of soup for roughly the calories of one.
- I learned one of my favorite tips from Dr. Joel Fuhrman in his book Eat to Live. He suggests sautéing with water. Instead of using oil to sauté vegetables at the beginning of a recipe, you add a couple of tablespoons of water to the pan. This works for starting soups or stir-fries. You can also use a couple of tablespoons of broth from more flavor. I sometimes cover the pan to use the steam to cook the vegetables more quickly.
Below is a recipe for my favorite calorie-free drink: green tea lime cooler.
- 1 green tea bag
- 3 slices fresh lime, washed
- 1 tsp stevia
- Pour boiling water over tea bag in a mug. Steep 5 minutes.
- Meanwhile, squeeze lime over plenty of ice in a glass. Add stevia and drop the lime pieces in.
- Pour hot tea over the ice mixture and enjoy!
Free and Helpful Apps
Download an app to make your life easier.
- Mosley recommends My Fitness Pal, which is a calorie counter and exercise tracker. This helps to track fast day calories.
- My favorite app is Lose It, which is very similar to My Fitness Pal, but I love that Lose It lets me scan barcodes to automatically enter the calorie information. The database is huge. It even includes many produce labels. This makes calculating your 500 calories a cinch. I also use it if I am making a recipe. I scan each item to get the total for the whole recipe, then divide by my serving size. I don’t bother tracking calories for my feed days. You can also enter your weights into this program, and email reports to yourself.
Both apps are free and worth looking into!
- Mosley suggests that you don’t weigh yourself too often. Due to the nature of this diet, your weight can fluctuate 2 to 3 pounds each week.
- My suggestion is to weigh yourself and take some body measurements on the day you start. I like to measure my bust, waist, hips, thigh, calf, bicep, and a sucked-in-waist. Then weigh yourself the morning after the second fast in the first week (if you fast Monday/Wednesday, then weigh Thursday morning). From then on, weigh yourself every second week the morning after the second fast day for that week.
- I would take body measurements once per month. I suggest committing to a 5-week program, like Mosley did, and see where you are at, at that point. That is only 10 days of dieting!
Will This Diet Work if I Only Want to Lose 10 Pounds?
- Mosley was 187 pounds, and 5'11". For most people, this doesn’t sound like he would need to lose too much weight. He was able to get down to 169 pounds until his wife finally said, "stop!"
- Co-author Mimi was only 128 pounds and was able to drop to 119 pounds.
This shows that the diet can easily work even when there is not much weight to lose. Mosley claims that most calorie-reducing diets result in people losing 75% fat and 25% muscles. Maintaining the muscle mass helps keep the metabolism up.
Risks and Benefits of Intermittent Fasting
- Studies show that "intermittent fasting," as one does on this diet, may help the brain ward off neurodegenerative diseases like Alzheimer’s and Parkinson’s while at the same time improving memory and mood. Cutting back on calories for just five days a month may prevent or treat age-related illnesses like heart disease and diabetes.
- A study at the University of Southern California found that cancer patients receiving chemotherapy may benefit from periodic fasting, which triggers the body to regenerate damaged immune system cells.
- Nutritional scientists at the University of California, Berkeley, however, found that men may respond better to intermittent fasting than women. In their study, women experience glucose spikes while fasting.
- Other nutrition experts warn that intermittent fasting can encourage eating disorders and may raise cholesterol levels.
If you are lucky enough to reach your ideal weight, but would like to continue fasting for the other health benefits, Mosley suggests switching to a 6:1 plan, where you fast one day a week.That is what he did, and tests showed that he was still in the low-risk category for disease due to the low level of IGF1 (insulin growth hormone) in his blood.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
© 2013 kitkat1141
Ash on March 23, 2018:
Hi it's recommended in our religion Islam to fast on Monday and Thursday.it was the practice of our prophet peace be upon him..definitely works
Lora on July 04, 2016:
The article is really good and useful. I think I am goint to try this method to maintain my new weight - I have recently lost 15 kilos on Dr Simeons diet with Anat Stern http://www.simeonsdiet.co.uk/, and I was just thinking that I want to eat too much sometimes, but I do not wanna go back to my old weight. So I guess this diet is a good option for me :)
kitkat1141 (author) from Ontario, Canada on May 06, 2016:
Hi Mary. Thank you for looking. If Friday is your fast day, you will only have 500 calories all day Friday, including dinner. You will break the fast Saturday morning. I know 500 calories sounds like you will be hungry, but I promise you can avoid those hunger pains by choosing very low calorie but filling foods. 2 cups of arugula have 15 calories, 2 cups of chicken broth have 14 calories. Get a good selection of herbal teas to sip on all day, hot or over ice. I find the next day I get full quickly. I serve up a regular serving size, but usually eat half the amount, and save the other half for later. If you are new to fasting, you could start with 750 calories the two fast days to adjust to eating low calories. Of course your results will be slower. Weight watchers is a perfect accompaniment to the 5:2 diet. Don't forget, there are many other benefits to intermittent fasting like lowering your risk of several cancers, diabetes and Alzheimer's. Good luck. Let us know how it works for you!
Mary on May 05, 2016:
I'm hoping you can clarify something for me as far as timing of the 5:2. Hypothetically speaking, if I have dinner at 6pm on Thursday, as a "feast day", then would my "fast day" end at 6pm on Friday, as that is 24 hours?
I was hoping I would eat dinner Thursday, and then space out the 500 calories throughout Friday, starting at 10am, which would give me 16 hours straight fast, eating 500 calories between 10 and 6, so I could then start my next "feast" day with a healthy dinner Friday night. Is this accurate?
Or would it go from 6pm Thursday fasting all day Friday with the 500 calories and Saturday morning would break the fast...although that would be closer to 32 hours?
I am currently doing Weight Watchers, which has shifted to mindful, clean, healthy eating, and would like to incorporate 5:2 into my meal plans each week. I guess I am just confused if a "day" is a 24 hour period, or if a "day" is a calendar "day". Thanks!
kitkat1141 (author) from Ontario, Canada on May 11, 2013:
Thanks for looking. Best of luck in your weight loss adventures. I can certainly relate. I gave this diet the 5 week trial like Mosley did in the documentary and lost 11 pounds. I was quite pleased. After the first few fast days, I was shocked how well I could survive a 500 calorie day! This is the first diet I have read about that seems to have so many other health benefits.