The Promise
"Fast," in this case, is not about speed. It's about fasting.
This diet, which started in the U.K., slashes your calories so drastically 2 days a week that you're basically fasting. That's not safe for everyone, so you should check with your doctor if you're considering trying it.
The Fast Diet says that you shouldn’t fast if you’re pregnant or underweight, or if you have a history of eating disorders or diabetes, and that you should check with your doctor first if you take medication. The diet also isn't recommended for kids, teens, frail seniors, or anyone who isn't feeling well or has a fever.
The basic concept behind The Fast Diet by Michael Mosley, MD, and Mimi Spencer is to eat normally for 5 days per week and eat very restricted calories on the other 2 days.
Mosley tried this "intermittent fasting" diet when his doctor showed him that though he was only a few pounds overweight, his cholesterol was high and his blood sugar was headed in the wrong direction. He writes that he knew fasting would be difficult, but his hunger pangs passed quicker than he expected. He also felt that fasting sharpened his senses and his brain. Plus, the diet delivered all the results he hoped for.
On its website, the Academy of Nutrition and Dietetics says that although there is evidence that intermittent fasting diets may help prevent chronic disease, more research is needed. It doesn't recommend the diet because "it is not a realistic long-term solution.” The academy also notes that "any variation of fasting may make a person irritable, cause daytime sleepiness/sleeplessness at night, and can even lead to dehydration."
What You Can Eat and What You Can't
You eat normally 5 days a week, and fast for the other 2 days. Your fasting days should not be back-to-back; you should have at least 1 normal eating day in between them.
During your fast days, you can eat, but not very much. Women get 500 calories per day; men get 600. That’s far less than what’s usually recommended. Depending on age, gender, and how active you are, you could need three or four times as many calories.
The Fast Diet encourages you to eat lean protein, vegetables, and fruit on fasting days, usually as two small meals plus a few snacks.
A typical 500-calorie fasting day might include oatmeal with fresh blueberries for breakfast, a tangerine for a snack, and a chicken and vegetable stir-fry for dinner. You will drink lots of water and may also have calorie-free beverages such as tea, coffee (no milk or sugar), and club soda.
On your 5 "off days," you can eat anything. Surprisingly, the research team that studied the diet found that people didn’t gorge themselves on off days.
The Fast Diet strongly discourages drinking alcohol on fasting days and suggests that if you drink on your "off days," you drink only in moderation. And once you reach your weight loss goal, 1 day of fasting per week is recommended for maintenance.
Level of Effort: Medium
Cooking and shopping: You’ll cook or eat as usual on off days, and with a very restricted menu on fasting days. The book provides a month’s worth of fasting day menus and recipes.
Packaged foods or meals: No.
In-person meetings: No.
Exercise: The Fast Diet recommends exercise, but the diet's website cautions that you shouldn't try to do a lot of endurance training on fasting days, and to stop if you feel uncomfortable.
Does It Allow for Dietary Restrictions or Preferences?
You can adjust the plan for vegetarian, vegan, and gluten-free needs on fasting days. But the book doesn't give you specific plans for those diets.
What Else You Should Know
Cost: Just your groceries.
Support: You do this diet on your own, but you will find lots of tips and discussion forums online.
What Dr. Michael Smith Says:
Does It Work?
Even though many health experts don’t recommend fasting, if you’re going to do it, the authors of this plan have it right. Eating 500-600 calories a couple of days a week will be tough, but it’s doable.
One reason experts tell people not to cut way back on calories is that it can slow your metabolism, making it even harder to lose weight. But studies show that fasting from time to time can be an effective strategy for weight loss. In addition, cutting calories on a couple of days instead of every day may help preserve muscle, so you lose mostly fat.
Mosley’s team found that people don’t overindulge on the non-fasting days. Other research suggests they may be right. But it’s ultimately up to you to make sure you don’t sabotage your weight loss efforts on the “off” days.
Is It Good for Certain Conditions?
If you have diabetes, this is absolutely not the weight loss plan for you. It could be dangerous, especially if you take medicine, and lower your blood sugar into unsafe -- even deadly -- territory.
For others, there are some early studies that show it may help improve some risk factors for heart disease, including blood pressure and cholesterol. Though any weight loss plan that drops the pounds is likely to also have this effect.
Talk to your doctor first before trying a fasting diet. This approach could put extra stress on your body.
The Final Word
If fasting interests you, The Fast Diet is a decent approach. It’s going to take some serious willpower, but if you’re up for the challenge, it can work. It’s definitely not meant for everyone, so don’t ignore the warnings.
It also may be tough to stick with in the long term. But trying it out to see if it suits you is a worthy plan. Have another plan in your back pocket if you or your body tires of this approach.
As a dedicated enthusiast in the field of nutrition and intermittent fasting, I bring a wealth of knowledge and expertise to shed light on the concepts discussed in the provided article. With a deep understanding of the science behind fasting and its potential effects on the body, I aim to provide valuable insights into "The Fast Diet."
Firstly, the concept of intermittent fasting, as presented in The Fast Diet, involves alternating periods of regular eating with periods of significant calorie restriction. The approach, advocated by Michael Mosley, MD, and Mimi Spencer, originated in the U.K. The central idea is to consume a normal diet for five days a week and drastically reduce calorie intake on the remaining two days. This form of intermittent fasting is designed to promote weight loss and potentially offer health benefits.
Michael Mosley's personal experience with the diet adds a layer of credibility to its effectiveness. His journey, highlighted in the article, began when faced with high cholesterol and unfavorable blood sugar levels despite being only slightly overweight. The positive outcomes he experienced, coupled with the potential cognitive benefits and improved senses, contribute to the diet's allure.
It's crucial to note that The Fast Diet isn't universally recommended. The Academy of Nutrition and Dietetics acknowledges some evidence supporting intermittent fasting's potential in preventing chronic diseases but refrains from endorsing it as a realistic long-term solution. Concerns include potential irritability, daytime sleepiness, and dehydration associated with any variation of fasting.
The eating pattern of The Fast Diet involves normal eating for five days and restricted calorie intake (500 calories for women, 600 for men) on the two fasting days. During fasting days, emphasis is placed on consuming lean protein, vegetables, and fruits in small meals and snacks. On non-fasting days, individuals can eat anything they desire. The diet discourages alcohol consumption on fasting days and advises moderation on non-fasting days.
The level of effort required for The Fast Diet is considered medium. Cooking and shopping involve regular activities on non-fasting days, with a limited menu on fasting days. The plan accommodates dietary preferences such as vegetarian, vegan, and gluten-free needs on fasting days.
As for its efficacy, the article cites Dr. Michael Smith, who suggests that while fasting a couple of days a week can be challenging, it is a viable strategy for weight loss. The potential preservation of muscle mass and effective fat loss are highlighted, addressing concerns about metabolic slowdown associated with prolonged calorie restriction.
However, The Fast Diet may not be suitable for everyone. Individuals with diabetes are explicitly warned against attempting this weight loss plan due to potential dangers, especially if they are on medication. While some early studies indicate positive effects on heart disease risk factors, the article emphasizes the importance of consulting with a doctor before embarking on a fasting diet.
In conclusion, The Fast Diet presents a unique approach to intermittent fasting, supported by both personal experiences and some scientific evidence. While it may not be a one-size-fits-all solution, individuals intrigued by fasting can consider it with caution, consulting their doctors and being mindful of potential challenges in the long term.
