Intermittent fasting has been gaining steam over the past decade or so, moving from a re-emerged trendy "fad diet" to a potentially healthy way of eating, backed by a growing body of research.
One particularly compelling review of the science so far, published December 2019 in The New England Journal of Medicine, found that IF is linked to weight loss, lower blood pressure, improved mental state, reduced inflammation and improved cellular repair. It may even be a boon for those looking to lose belly fat.
(One weakness of the science, pointed out by the researchers, is that there's not enough long-term studies in humans to evaluate the affects across a lifespan.)
While the research is promising, intermittent fasting can be tricky if you're new to this way of eating. It's also not suitable for everyone.
Avoid these eight common IF mistakes that could stall weight loss or even put your health in jeopardy.
1. The Mistake: Doing Too Much Too Soon
While the variety of options is great because one size doesn't fit all when it comes to eating and diets, jumping right into an extreme approach like OMAD isn't the best idea. It can be shocking for your body, and you're a lot less likely to stick with it.
The fix: Think about approaching IF like you would a fitness goal. If you're new to running and you start to train for a half marathon, the best and safest approach is not going for a 10-mile training run right out of the gate. By doing this, you would be putting yourself at risk for injury, let alone the very real potential that you might not finish.
The same goes for intermittent fasting. Consider where you're starting and make adjustments to your eating from there.
If you normally eat throughout the day, for example, you might want to start with shaving off an hour or two at night. So if you normally eat up until 7 or 8 p.m., considering trying not to eat after 6 p.m. Start with small changes and make adjustments slowly, as you adapt.
2. The Mistake: Picking the Wrong Plan
Be realistic about your current lifestyle and what is feasible for you. For example, the 5:2 method (eating 500 calories per day two days a week, and eating normally the other five days) might not be the right approach if you're training heavily or if you just like to have routine in your life.
The fix: A better approach might be the 16:8 method, where you have an eight-hour window to eat throughout the day. This is easier to plan for around meal times with your family or your training schedule, and it allows for a more consistent eating routine.
3. The Mistake: Treating Your Eating Period as a Free-for-All
Fasting for 18 hours does not mean you can dive into a deep-dish pepperoni pizza and ice cream and expect the same benefits of IF. By doing this, you're setting the stage for numerous problems: potential binge-eating, fat gain and post-meal digestive issues.
The fix: Plan your meals ahead of time and aim for healthy, balanced meals that include vegetables, fruits, whole grains, lean proteins and healthy fats. Your window of eating opportunity is limited, so you want to make every bite count.
4. The Mistake: Not Eating Enough
Because the amount of time you're "allowed" to eat is limited, it can be hard for some to eat enough — especially enough of all the nutrients your body needs. This puts you at risk for nutrition deficiencies and potentially stalled weight loss.
The fix: Planning your meals can help ensure you're eating enough of the right foods. If you find you're eating too few calories, consider adding more nutrient- and calorie-dense foods like avocados and nuts. You may also need to extend your eating window if you find you're not able to eat enough.
5. The Mistake: Exercising at the Wrong Time
If you're following the 5:2 method, you probably don't want to plan a strenuous workout on the day you're only consuming 500 calories. These two days a week would serve better as your rest days.
The same goes for other methods like 16:8. You don't want to work out later in the evening when you're not able to refuel properly afterwards.
The fix: Make sure your eating windows and workout times are compatible.
Recovery nutrition, or eating post-workout, is crucial because it allows your body to refuel and rehydrate as well as help your muscles repair and grow. Eating post-training also helps your body adapt from the training session and supports your immune system, according to the Sports Dietitians of Australia.
Skipping recovery nutrition can make you more tired overall, increase muscle soreness and put you at an increased risk for injury as well as limit your potential gains from the training session.
6. The Mistake: Scheduling Your Eating Window for Later in the Day
Whether you're following OMAD, the 5:2 method or 16:8, skipping meals earlier in the day and eating more of your calories later in the afternoon or evening may not be serving you. While it's important to pick a plan that works with your schedule, research shows eating later in the day may not be the best approach for weight loss.
The fix: Eat more in the a.m. than p.m. Indeed, a July 2019 study published in Obesity found that eating early in the day and stopping in the afternoon reduced hunger hormones and decreased appetite compared to eating early and continuing on later into the evening.
And a March 2020 study published in The Journal of Clinical Endocrinology & Metabolism furthers these results. It found that when more calories are consumed in the morning versus later in the day, the diet-induced thermogenesis — or the increase in metabolism post-meal — was 2.5 times higher. And appetite, especially for sweets, was increased in those who consumed more of their calories later in the day.
7. The Mistake: Not Giving Yourself Any Flexibility
Intermittent fasting needs to work with your life, and if you strive for absolute compliance, you'll likely crash and burn.
The fix: Change comes with consistency, not perfection. If you really want to give IF a go, give yourself some flexibility.
If you have a celebration or a social outing with friends, don't skip out on enjoying the cake or dinner on account of it being outside of your eating window. Give yourself some wiggle room to enjoy these important moments.
8. The Mistake: Attempting Intermittent Fasting When It’s Not Appropriate
Intermittent fasting isn't for everyone, and in fact, it might be dangerous for some people, including women who are pregnant or breastfeeding and anyone with a history of disordered eating.
IF can also be dangerous for people with chronic conditions such as diabetes, according to Harvard Health Publishing. Also, if you're taking certain medications for heart disease, blood pressure or diabetes, you may be at risk for electrolyte abnormalities and altered glucose levels.
The fix: Working with your doctor or a dietitian will help ensure you're attempting IF and weight loss safely.
- The New England Journal of Medicine: "Effects of Intermittent Fasting on Health, Aging, and Disease"
- Sports Dietitians of Australia: "Recovery Nutrition"
- Obesity: "Early Time‐Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans"
- The Journal of Clinical Endocrinology & Metabolism: "Twice as High Diet-Induced Thermogenesis After Breakfast vs Dinner On High-Calorie as Well as Low-Calorie Meals"
- Harvard Health: "Not So Fast: Pros and Cons of the Newest Diet Trend"