Intermittent Fasting: Surprising Update
- By Monique Tello, MD, MPH, Contributor
Theres a ton of incredibly promising intermittent fasting research done on fat rats. They lose weight, their blood pressure, cholesterol, and blood sugars improve but theyre rats. Studies in humans, almost across the board, have shown that IF is safe and incredibly effective, but really no more effective than any other diet. In addition, many people find it difficult to fast.
But a growing body of research suggests that the timing of the fast is key, and can make IF a more realistic, sustainable, and effective approach for weight loss, as well as for diabetes prevention.
If You Need To Lose Weight A Diet That Focuses Mainly On When You Eat May Be A Good Way To Shed Pounds And Improve Your Cardiovascular Health
Anyone who’s tried different weight-lossdiets is probably familiar with their pitfalls. Low-calorie diets often leave you tired, hungry, and cranky. Low-carb or “keto” diets can cause cravings and constipation. Low-fat diets are also tough to follow and, contrary to popular belief, they do not seem to prevent cardiovascular disease.
Another diet trend, intermittent fasting, takes a different approach. Rather than limiting what you eat, this diet limits when you eat . For some people, that change may be easier to manage, says Dr. Eric Rimm, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health.
Short-term studies suggest that people stick to intermittent fasting diets as well as or better than they do to other diets. And according to a 2019 review article in the journal Nutrients, intermittent fasting promotes weight loss and may reduce risk factors linked to heart disease, including diabetes, high blood pressure, unhealthy blood lipid levels, and inflammation.
“However, we don’t have much evidence about how well this diet works over the long term,” says Dr. Rimm, noting that there are just two long-term studies of intermittent fasting, each lasting a year. Nor are there large populations of people who’ve followed this eating pattern for years. That’s in contrast to two other diets linked to a healthy heart and healthy body size the Mediterranean diet and a vegetarian diet.
What Types Of Intermittent Fasting Plans Lead To Weight Loss
The review included studies on three types of intermittent fasting:
- Alternate day fasting , which typically involves a day of unrestricted eating alternated with a fasting day where 500 calories consumed in one meal account for the total daily calorie intake
- The 5:2 diet, a modified version of alternate day fasting that involves five feasting days and two fasting days per week.
- Time-restricted eating , which limits eating to a specified number of hours per day , followed by 16 hours of fasting
Its worth noting that the review wasnt designed to compare the effectiveness of different types of intermittent fasting plans because the studies were done in different groups of people and using different parameters. But the results did indicate that individuals who followed either the alternate-day diet or the 5:2 plan both averaged a loss of around 7 percent of their body weight , and were able to maintain that loss for a year. Despite fasting much less frequently than alternate-day fasters, subjects who participated in the 5:2 diet lost an equivalent amount of weight, a finding that surprised researchers.
While all plans led to some weight loss, following a time-restricted eating plan was the least effective plan for shedding pounds. In total, participants with obesity who followed a time-restricted eating plan lost an average of 3 percent of their body weight.
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Meal Timing: Is Intermittent Fasting The Best Strategy
Breakfast has been touted as the most important meal of the day. However, in recent years, intermittent fasting has become a mainstream option for individuals trying to lose weight or improve their overall health.
Intermittent fasting often means skipping the typical time for breakfast, pushing the break fast meal until noon or later.
So, whats the deal? Is it better to eat breakfast in the morning or skip it? Beyond the challenge of choosing what to eat, the decision of when to eat adds another level of complexity.
Choosing a more nutritious lifestyle should feel accessible, rather than complicated and it can! The truth is, the best diet plan and meal timing plan is the one that works for you. There are several individual factors to consider when choosing the food that will work best with your body, and the same goes for choosing meal timing. The more information you have on intermittent fasting, the better youll be able to decide if its something that would benefit your lifestyle.Lets dive into the details.
When Can I Eat On The : 8 Diet
You can pick an 8 hour window to suit your day. So, for example it could be between 10am 6pm or 11am 8pm and so on. Plus, you can still drink tea and coffee outside of those hours too, although because of the benefits of drinking water you are also encouraged to stay as hydrated as possible.
Most people choose to fast through the night, and opt to eat their first meal at about 11am or in the middle of the day.
Tom says, The most common hours adopted for the eating period is 12 till 8pm. The reason for this is because people arent normally that hungry in the morning, you dont want to be consuming too many calories during the evening and this allows us to eat our lunch and dinner as well as a healthy snack.
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Youre Not Getting Enough Caloriesor Youre Getting Too Many
Time-restricted eating is exactly that: Youre restricting the timeframe for eating. While it can be used along with calorie reduction, its not meant to be a diet in itself, says Fung.
If youre cutting way back on calories with fasting, then its likely going to backfire, he adds. Thats because restriction has a tendency to make you swing hard in the other direction, toward a binge. When that happens often enough, you may get stuck in a yo-yo pattern that has been shown to have significantly negative effects on your health, especially on cardiovascular function.
Another potential hazard is overeating, since youre trying to smush all your calories into a shorter timeframe. This doesnt mean youre in a binge every day, but you may be eating more than youd planned because youre concerned about being hungry during your fasting window.
Fung suggests setting your calorie intake needs firstbased on factors like your age, weight, and level of activityand then making sure you meet those calorie needs within the timeframe youve chosen. Chat with a registered dietitian or other medical professional if youre not sure how many calories you should fuel with each day.
What If I Cant Go That Long With A Fast
Lets say you decide to follow the 16:8 protocol, but youve been used to eating every 2 4 hours. This is common because weve been told for years that eating every 2 4 hours keeps our bodies from going into starvation mode. I get it, Ive been there.
First of all, the whole idea of starvation mode is true. But, it pertains to your body burning fewer calories when you reduce caloric intake over the long term. Your body is not going to hold on to fat because you let more than a few hours go by without eating. In fact, the opposite happens. By fasting, you allow your body to access and use stored fat for energy.
So, try to ease yourself into it. Start with a 12-hour fast that begins after your last meal and ends when you wake up. Maybe all youre doing here is replacing an evening snack with decaf tea or coffee.
As your body adjusts, you can extend the fasting period until you reach 16 hours. When youre accustomed to fasting 16 hours, feel free to extend the fast further. This is only if you want to, its not necessary.
My point is that you will benefit more from starting small and being consistent, than from going full throttle and failing to follow through.
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You Are Not Eating Enough Protein
If you find that your meals cannot carry you across your fasting period to your next eating window, then you might need to adjust your diet.
Consider including more lean protein in your diet. It does not matter the type of protein, vegan and animal protein, all are fine.
Proteins can help keep you full till your next meal. Furthermore, if you are exercising during this period, proteins are important for building your muscles and protecting your bone health.
Your meals should have healthy fats, carbs, leafy greens, and proteins.
Intermittent Fasting For Pre
The one time that intermittent fasting may be able to help professional bodybuilders, is when theyre trying to cut down before a competition. If this is the case, then intermittent fasting can be a useful asset, particularly as it may help with lipolysis and increase your daily energy expenditure.
The major key here is to still get enough protein and calories, which shouldnt be hard if youre consuming good foods, in addition to a good whey protein when needed. In general, you should aim to consume 1 gram of protein per pound of your goal lean body weight.
For a pre-competition cut, the 16/8 intermittent fasting method is the best by far, because it will essentially allow you to do 3 things effectively:
So, if youre a natural professional bodybuilder, doing intermittent fasting may be a great alternative to the conventional 6 meals a day diet that most bodybuilders follow.
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How Long Can We Last Without Food
Once you start fasting, you may feel ravenously hungry as your mind is flooded with images of your muscles disintegrating into thin air. This is simply how your mind reacts to the threat of starvation just because it feels like you will lose all your muscle and starve doesnt mean you will.
In fact, Mahatma Gandhi survived for 21 days without food while only taking in sips of water. During times when people had no food or water at all, they were able to survive for 10 to 14 days. However, these are just anecdotes what does the science say?
Many studies have been done during hunger strikes and religious fasts confirming that humans have the capacity to survive even longer than Gandhi did during his fast.
One monk, for example, set out to do a 40 day fast with medical supervision while maintaining his daily activities in the monastery. After 36 days, the medical professionals had to step in due to profound weakness and low blood pressure when standing. Although the monk fasted for 15 days longer than Ghandi, the medical professionals were able to stop the fast in time so that he could recover.
Another study tracked 33 political prisoners who were on hunger strike. The prisoners fasted for 6-24 days before being hospitalized for dehydration due an inadequate intake of fluids and electrolytes . Breaking their fast was described as being uncomplicated.
Getting Started With Intermittent Fasting: Next Steps
Intermittent fasting can potentially have some very positive benefits for somebody trying to lose weight or gain lean body mass.
Men and women will tend to have different results, just like each individual person will have different results. The ONLY way to find out is through a conversation with your doctor and self-experimentation.
There are multiple ways to do an Intermittent Fasting Plan:
- Fast and feast regularly: Fast for a certain number of hours, then consume all calories within a certain number of hours.
- Eat normally, then fast 1-2x a week: Consume your normal meals every day, then pick one or two days a week where you fast for 24 hours. Eat your last meal Sunday night, and then dont eat again until dinner the following day.
- Fast occasionally: probably the easiest method for the person who wants to do the least amount of work. Simply skip a meal whenever its convenient. On the road? Skip breakfast. Busy day at work? Skip lunch. Eat poorly all day Saturday? Make your first meal of the day dinner on Sunday.
After that, get started! Take photos, step on the scale, and track your progress for the next month.
See how your body responds.
See how your physique changes. See how your workouts change.
And then decide if its something you want to keep doing!
4 years later, I have no plans on going back to eating breakfast. Sorry General Mills and Dr. Kellogg!
If youre worried about all of this stuff, or arent sure when to eat and stop eating, try out our new app!
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Different Methods Of Intermittent Fasting
There are many different ways to implement an intermittent fast but weve provided a select few options from our calculator which include
- 16/8 method
So, youll simply type in the required information based on your approach and goals, then youll be provided with some details which you can follow that will make your efforts much simpler.
Is Intermittent Fasting Healthy
Is intermittent fasting safe? Remember that youre only supposed to fast for 12 to 16 hours and not for days at a time. Youve still got plenty of time to enjoy a satisfying and healthy diet. Of course, some older women may need to eat frequently because of metabolic disorders or instructions on prescriptions. In that case, you should discuss your eating habits with your medical provider before making any changes.
While its not technically fasting, some doctors have reported intermittent fasting benefits by allowing such easy-to-digest food as whole fruit during the fasting window. Modifications like these can still give your digestive and metabolic system a needed rest. For example, Fit for Life was a popular weight loss book that suggested eating only fruit after supper and before lunch.
In fact, the authors of this book said that they had patients who only changed their eating habits with this 12- to 16-hour fruit fast each day. They did not follow the diets other rules or count calories, and they still lost weight and got healthier. This strategy might have simply worked because the dieters replaced junk food with whole foods. In any case, people found this dietary change effective and easy to make. Traditionalists wont call this fasting however, its important to know that you may have options if you absolutely cant abstain from food for several hours at a time.
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Intermittent Fasting Why Meal Timing Matters
Simply put, intermittent fasting is the dietary strategy of restricting your food consumption to a specific window of time. For example, one of the most common intermittent fasting approaches is fasting during an 18-hour window of time and eating during the 6-hour window of time that is left in the day.
Lets say your last meal was at 6 pm last night and you ate nothing else after that. To implement an intermittent fast, simply restrict eating until 12 pm the next afternoon . To do this every day, only eat between 12 pm and 6 pm and fast for the remainder of the day.
There are many different variations of intermittent fasting as well. Dr. Dom DAgostino, a well-known ketogenic diet researcher, suggests doing a longer intermittent fast for 3 days, 3 times a year. This means not eating for 3 days, and eating normally until the next fast.
Another way to try fasting for yourself is by incorporating intermittent fasts of 16 or more hours per day into your lifestyle. This is a much more accessible strategy that allows you to experience many of the benefits of taking a short break from calories.
Despite the simplicity of this concept, it may not be readily apparent how beneficial intermittent fasting can be for you, especially if you are already benefiting from the ketogenic diet.
Does Intermittent Fasting Work For Everyone
Varady and her colleagues hoped the review would help debunk some myths regarding intermittent fasting. Two such myths that intermittent fasting negatively affects metabolism, and that it causes disordered eating are not true, according to the studies reviewed. People are often concerned that fasting will make them feel lethargic and unable to concentrate, says Varady. Yet many people in these studies reported experiencing a boost of energy on fasting days, she says.
Although its different for each person, I would say that its a very small subset of patients who really notices improved mental clarity or energy with intermittent fasting, says Fatima Cody Stanford, MD, MPH, associate professor and obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School in Boston, who was not involved in the review. Many people dont feel great while they are fasting for a variety of reasons. In some cases, their blood sugar might get too low during the fasting period, she says.
There are several groups who should not fast, according to the studies. Those individuals include:
- Those who are pregnant or lactating
- Children under 12
- Those with a history of disordered eating
- Those with a body mass index, or BMI, less than 18.5
- Shift workers, who studies have shown have difficulty with fasting regimens because of the changes in work schedules
- People who need to take medication with food at regimented times