Thanks to buzz from the biohacking community (and thousands of weight loss success stories on Instagram), intermittent fasting has become one of the most influential diet protocols of our time. And while many fasting fans suggest that willingly abstaining from eating can benefit pretty much everyone, certain people may be better served by skipping breakfast than others.
The Background On Intermittent Fasting
While most diet protocols set parameters on what to eat, intermittent fasting concerns itself with when you eat.
Also known as IF, intermittent fasting involves alternating between intervals of calorie reduction or straight-up fasting and periods of normal eating. Different people bring IF to life in different ways, fasting whenever (and for however long) best fits their work, family, and social lives, says Dr. Josh Axe, D.N.M., D.C., C.N.S., co-founder of Ancient Nutrition and member of The Vitamin Shoppe Wellness Council.
Many people eat during about an eight-hour window—and fast for the other 16 hours. (Don’t worry—about half of those 16 hours are spent sleeping.) Others, meanwhile, might choose to eat normally most days and either fast completely or restrict calories (to less than 500) on two or three non-consecutive days. This is known as 5:2 fasting.
The Benefits Of Intermittent Fasting
As interest in (and research on) intermittent fasting booms, proponents suggest it supports everything from weight loss to cognitive function to longevity.
“The focused fasting time supports autophagy, the body’s way of clearing out old cells and making new cells,” says Holly Niles, MS, CNS, LDN, IFMCP. (Think of it as biological housekeeping.) Some research suggests autophagy helps remove cancerous cells and slows the aging process.
“Fasting also puts the body in more of a ketogenic state, in which the body uses fats for fuel rather than sugar,” Niles adds. “This state has been shown to improve cognition, promote weight loss, and even support blood sugar balance.”
Who Can Benefit Most From Intermittent Fasting?
As research on intermittent fasting continues to develop, experts believe the practice may offer especially impressive benefits to certain groups of people.
1. People With Type 2 Diabetes
Simply put, people with type 2 diabetes have trouble responding to the hormone insulin and maintaining healthy blood sugar. “Intermittent fasting trends the body towards using fat for fuel instead of sugar, which is very helpful,” says Niles.
Research—like one case series published in BMJ Case Reports—suggests IF can actually help reverse type 2 diabetes. (The BMJ Case Reports research highlights three men who eradicated their need for insulin treatment after 10 months of alternate-day fasting.)
2. People Who Are Overweight
While most forms of intermittent fasting restrict when you eat instead of what you eat, many fasters end up planning meals better—and eating fewer, healthier calories overall, explains dietitian Ellen McNamara, R.D., L.D.N. Over time, diets that involve a deficit in calories should yield weight loss.
Plus, since fasting typically signals the body to turn to fat stores for energy, it can be particularly beneficial for people with body fat to lose, says Niles.
A 2015 systematic review of 40 different studies (published in Molecular and Cellular Endocrinology) supports these claims, suggesting that fasting is just as effective as standard calorie-restrictive diets at promoting weight loss.
3. People Who Want To Support Brain Health
“Increasing ketone production, lowering insulin levels, and significantly improving insulin sensitivity all benefit the brain,” says Axe. “Higher ketone levels due to fasting may also fuel the brain better—and lead to increased memory retention and learning, emotional decision making, and sensory integration.”
According to Axe, these effects can help fasters feel sharper and more focused in the short-term—and have a protective effect against cognitive decline in the long run. Many fasters report feeling more clear-headed and productive while fasting—especially in the morning.
4. People With Digestive Issues
According to Niles, intermittent fasting gives the body a break from constantly digesting or managing all the food we eat. This break may help people avoid feeling overly full or bloated.
Eliminating the option to snack mindlessly at night also ensures digestion doesn’t interfere with your sleep.
Plus, fasting can help people pay better attention to hunger and fullness cues, which can be easy to lose touch with when we don’t have time restrictions set on when we do and do not eat, says Axe.
5. People Who Want To Limit Social Eating
If you tend to be laser-focused on eating well during the day, but go hog wild once you’re off the clock, intermittent fasting can provide beneficial guardrails, suggests McNamara.
For some people, committing to IF eliminates mindless munching late at night or going overboard on appetizers at happy hour. Do it right and you’ll be so satiated that you won’t even be tempted.
6. People Who Hate Counting Calories
If you’ve used calorie- or macro-counting in attempts to lose weight in the past, intermittent fasting may support your goals—without all of the food tracking and number crunching.
The beauty of IF is that you can eat until satisfaction during your eating window, and don’t have to nix entire food groups or count calories, says Axe.
Fasting Rules For The Road
Intrigued by intermittent fasting? Check in with yourself about whether it will seriously conflict with your lifestyle, recommends McNamara. For example, if you enjoy late dinners and drinks with friends, IF could impact your social life. Or, if you work out early in the morning, you might not want to wait until lunchtime to refuel.
Some people may also view their feeding windows as free-for-alls. These people may actually end up overeating and gaining weight on IF, says McNamara. (If this sounds like you, McNamara recommends logging your meals for a few days. This way, you can make sure you’re meeting your nutrient needs and keeping calories reasonable.)
Because of intermittent fasting’s highly restrictive nature, it’s not a healthy strategy for certain groups, including:
- pregnant or breastfeeding women
- type 1 diabetics
- people with a history of fainting or disordered eating
According to Axe, people who take medications for blood pressure or heart disease should also be cautious when fasting. (Taking these medications on an empty stomach may contribute to side effects.)
Ultimately, if you decide to try IF, what you eat during your ‘eating windows’ is entirely up to you. However, the usual principles of a healthy diet still apply. Focus on eating plenty of fresh fruits and veggies, foods high in fiber, healthy proteins, and unprocessed fats, says Axe. As always, avoid added sugar, refined grains, and processed foods as much as possible.
References & Further Reading
- The EMBO Journal: “Autophagy in malignant transformation and cancer progression.”
- Journal of Clinical and Experimental Pathology: “Autophogy: An Emerging Anti-Aging Mechanism.”
- BMJ Case Reports: “Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin.”
- Molecular and Cellular Endocrinology: “Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials.”