Intermittent fasting. You’ve likely heard of it or know someone who has tried it. Intermittent fasting is less focused on what you can and cannot eat and more so focused on when you eat. In a nutshell, intermittent fasting is the process of cycling through periods of fasting and “non-fasting” throughout the day aka voluntary abstinence from food or drink.
Example: Meals are eaten from 8am-3pm, with fasting during the remaining hours of the day. This is one method. Another is 5:2. The 5:2 diet calls for limiting your caloric intake to 500 calories two nonconsecutive days per week while eating a healthy diet in the normal caloric range (2,000 for women; 2,500 for men) the rest of the week.
We are going to get into the science and all of that good stuff BUT FIRST- lets conquer the “diet” culture issue.
It’s controversial- but it doesn’t have to be. Finding a diet that works means that it becomes easy for you and becomes your lifestyle. We are not all wired the same way which means not every type of “diet” will work for everyone. Intuitive eating works for us; however, we have seen patients that do well on ketogenic, intermittent fasting, weight watchers, etc. if you are following a diet correctly. If it works for you, if you find it easy, and you are able to create a lifestyle from it then go for it. A diet should be sustainable and make you feel healthy. It should not feel as if you are deprived. You should not be drifting away at work and obsessing about the foods you cannot eat. If this is you, you are on the wrong “diet” [and we don’t mean just being excited about your next meal- because who isn’t- no, we mean obsession].
But if your “diet” of choice is sustainable and keeps you from chronic disease/obesity- go for it. We give the word “diet” more power than it needs to have and to be honest we aren’t sure why. Diet: the kinds of food that a person habitually eats; therefore, technically, we are all following our own, personal “diet”. To try and put everyone in the same box, to try and say what works for one will work for all- isn’t the case, in our opinion.
With any lifestyle choice [including diet] moderation is key.
Example: with the ketogenic diet- make sure your sodium intake isn’t in excess. Be sure to watch your fat/cholesterol intake. With intermittent fasting- don’t be extreme, be moderate. Don’t fast for days [exceptions sometimes include religious purposes]. Fast because it fits in with your life and your schedule. Whatever makes your body feel good, is what is right for you.
In all honesty, Patrick and I have both seen people that have had wonderful outcomes with ketogenic, intermittent fasting etc. diets. We know of physicians and dietitians themselves on these diets. We know equally as many people who have gained weight from the diets and had a terrible experience. The difference between the people that do well and those who don’t is moderation. You shouldn’t be malnourished, obsessing, or wanting to binge on a gallon of ice cream whenever you get the chance. It should feel sustainable and simple. That’s what a realistic lifestyle change comes down to.
I love what a nutrition professor from Harvard University said,
“But intermittent fasting may have a beneficial effect on diet psychology for some people”, says Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women’s Hospital. “One of my patients felt strongly that he didn’t want to be bothered with tracking calories and filling out food records. Instead, he opted for a 5:2 fasting approach, which has worked well for him”. The main goal is to develop a healthy eating pattern that is sustainable, McManus says.
Before we get into details on intermittent fasting, right off the bat, unless working very closely with your physician, we would not recommend this lifestyle for diabetics [as meals and snacks with insulin schedule is crucial], pregnant women, or people with other medical illnesses. This information is not intended nor implied to be a substitute for medical advice, so please consult your healthcare provider if you have any questions or concerns.
Now back to details on intermittent fasting.
As with every diet, benefits are exaggerated and risks of taking the diet to an “extreme” are downplayed. That’s why knowing the science behind diets is important.
science behind intermittent fasting
“The idea is that during the fasting period, cells are under a mild stress and they respond to the stress adaptively by enhancing their ability to cope with stress and, maybe, to resist disease. Researchers compare this to vigorous exercise, which stresses, muscles and the cardiovascular system. As long as you give your body time to recover, it will grow stronger. There is considerable similarity between how cells respond to the stress of exercise and how cells respond to intermittent fasting.” – Mark Mattson, senior investigator for the National Institute on Aging, part of the US National Institutes of Health. Mark Mattson is also a professor of neuroscience in the Johns Hopkins School of Medicine.
findings from the studies
- Participants who adhered to the diet lost 8% of their initial body weight over 8 weeks. They also saw a decrease in markers of oxidative stress and inflammation, and improvement of asthma-related symptoms and several quality-of-life indicators.
- Intermittent restriction (fasting from 10-16hrs/day) was as effective as continuous restriction (5:2 method) for improving weight loss, insulin sensitivity and other health biomarkers.
- Mattson researched the protective benefits of fasting to neurons. If you don’t eat for 10–16 hours, your body will go to its fat stores for energy, and fatty acids called ketones will be released into the bloodstream. This has been shown to protect memory and learning functionality as well as slow disease processes in the brain.
- Even a single fasting interval (e.g., overnight) can reduce basal concentrations of metabolic biomarkers associated with chronic disease such as insulin and glucose.
- IF [intermittent fasting] has been linked to warding off neurodegenerative diseases like Alzheimer’s and Parkinson’s
- IF has been inked to improving memory and mood.
- Per a study done at UF, intermittent fasting caused a slight increase to SIRT 3, a well-known gene that promotes longevity and is involved in protective cell responses.
- The same UF study also showed intermittent fasting decreased insulin levels in the participants, which means the diet could have an anti-diabetic effect as well.
our take from this
We are going to be honest with you – it comes down to calorie intake. Whether it is ketogenic, intermittent fasting, weight watchers, low sugar, Mediterranean, etc- the above benefits are happening, to overweight and obese people, because they are losing fat. Getting rid of excess body fat will improve a person’s metabolic profile and lower cardiovascular risk but there’s no strong evidence that fasting adds health benefits beyond any other weight-loss strategy. If you are already a healthy weight- you already have those benefits mentioned above.
This is why it comes down to you. It depends on what works for you and what is sustainable. It depends on what motivates you. The second your “diet” becomes an unhealthy cycle of restriction and obsession, you lose every single health benefit. Happiness is moderation. Practice discipline without obsession. Do not let your diet define you. Focus on health and nourishing your body. Find your motivation to eat healthy whether that is to avoid chronic disease, feel better about yourself, or to just live your best damn life.
Our best diet recommendation: Increase your fruit + vegetable consumption to 10+ cups a day. Everything else is up to what works for you and what keeps you mentally and physically happy and healthy.
http://easacademy.org/trainer-resources/article/intermittent-fasting
http://news.ufl.edu/archive/2015/02/feast-and-famine-diet-could-extend-life-study-shows.html
Doctor Meets Dietitian 
This is a very interesting post. We were just talking about this at work yesterday, I will be sharing this with them. I really like the end, the best diet recommendation. When you are mentally and physically happy and healthy you can truly accomplish anything.
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Thank you so much for the feedback!! It was definitely a challenge to balance our thoughts but also make sure we always confirm with science! The ending is our personal fav too! Thank you again!!!
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Great article! I really appreciate your balanced approach and review of the science. I personally practice intuitive eating but I have realized that some of my patients want a more structured approach to their diet, and some of them have had success with practicing a modified version of intermittent fasting. I think part of the reason it’s successful though is that people stop eating so many empty calories between and after meals!
Is there any evidence that intermittent fasting is good for brain health/aging beyond the weight loss aspect? I.e. if someone didn’t need to lose weight would intermittent fasting have any benefits?
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