Fasting is increasingly popular, but what is it, and is it actually safe to try? Depending on your unique circumstances, intermittent fasting may be a legit strategy to lose weight and keep it off. Of course, the best weight-loss solution is one you can stick to.
This strategy is not without its concerns or dangers. Learn about the different intermittent fasting plans and get tips to start your fasting journey safely.
What Is Intermittent Fasting?
Fasting is going without food or nourishment for a set amount of time. In fact, you fast every night when you sleep, and break that fast every morning with “breakfast,” hence the name. It’s nothing new — people fast for routine blood tests, religious holidays, and spiritual growth.
Intermittent fasting, though, refers to structured strategies you can use for weight loss and body-fat reduction. Research findings show this can be an effective strategy for short-term weight loss, but the actual results depend on the plan you choose and how well you stick to it.
Well-known intermittent fasting plans include:
- The 16/8 Method: You do a 16-hour fast daily and have an 8-hour window to eat. For more information on this method: 16/8 Fasting: Here’s What You Should Know.
- Time-Restricted Feeding (The Warrior Diet): You do a 20-hour fast and eat one big meal each day.
- Complete Alternate Day Fast (Eat-Stop-Eat): You do a 24-hour fast every other day with no calorie-containing foods during the fast. Eat what you like on non-fasting days.
- The 5:2 Diet: You do one to two fasting days each week. This is a modified fasting diet meaning you can eat 500–600 calories during fasting days.
How Do I Get Started With Fasting?
Some people like intermittent fasting because they can build a calorie deficit for weight loss without counting calories or portioning their food. If you’ve struggled with this in the past, it might be worth considering intermittent fasting.
The usual caveat applies: It is not recommended for pregnant or nursing women, children, people with a chronic disease (e.g., diabetes, high blood pressure, low blood pressure), or those prone to an eating disorder. When in doubt, consult a medical professional.
1. Choose your fasting period.
First and foremost, choose a plan you can stick to. If you’re new, try the 16/8 method. It may be easier to follow since you’re asleep for eight out of the 16 fasting hours. An added benefit: Research suggests this method aligns with your body’s circadian rhythm, which may mean less disruption for your metabolism.
Should you feel uncomfortable with such a long fast, start out with a shorter, say, 10-hour fast, and ramp up the fasting period over time. Think of it like training for a marathon — without proper preparation, you may not enjoy it.
2. Hydrate all around.
Have as much water as you want during your fast. If you’re not used to fasting, you may already be feeling hungry and uncomfortable. Preventing dehydration and its associated symptoms (e.g., tiredness, lightheadedness, dry mouth) will make the process more pleasant.
Wondering how much you should be drinking? Use your body weight to determine that amount. Just divide your body weight in pounds by two, and aim for that many ounces of fluid daily. Of course, you may need more if you’re sweating hard from exercise or hot weather. In these cases, let your thirst guide you.
3. Keep busy.
Before fasting becomes a habit you may find yourself daydreaming of food. If you’re at work, it shouldn’t be too hard to divert your focus elsewhere. Otherwise, your best bet is to fill up the time with an activity you enjoy. Healthy distractions include meditation, reading, listening to good music, or picking up a hobby.
4. Rethink your workout plan.
Ideally, don’t exercise during your fast. It’s OK to work out on an empty stomach, but it’s hard to sweat at your best. As Denis Faye, MS, Openfit’s executive director of nutrition will tell you, “If you can’t ‘bring it’ the way you normally do, are you truly benefiting? Likely not.”
Some research does show that fasted-state training can promote fat burning, especially for endurance folks. If this is you, by all means, keep your original workout schedule.
5. How to control your hunger: Eat more fiber and protein.
These nutrients are known to help keep you full while you cut calories with intermittent fasting. Here’s how: Fiber adds bulk to your meals and slows down digestion. Protein offers satiety and helps maintain muscle mass as you’re losing weight, which helps keep your metabolism up overall. Science lesson over. Go break your fast with whole fruits, vegetables, whole grains, lean meats, seafood, and tofu or tempeh.
6. Portion control intuitively with hunger.
With most intermittent fasting plans you will not need to count calories or measure out food. But, you will still need to create a calorie deficit to lose weight. Instead of eyeballing your meals, pay attention to how hungry you feel after you’re done eating. Your goal is to feel satisfied, not stuffed. You may be rusty at first, but getting in touch with your hunger signals is how you learn to eat the right amount for your body.
What Can I Eat on My Fast?
The point of fasting is to abstain from food, but you can have all the calorie-free beverages you like. This includes water and all unsweetened coffees and teas. On modified fasts, such as the 5:2 diet, you can eat between 500–600 calories during fasting days. Since it’s easy to hit this number of calories (a small wheat bagel with two tablespoons of cream cheese and a 12-ounce glass of OJ will do it), you may need to count calories on those days.
When Should I Stop Fasting?
Be warned that some uncomfortable side effects of intermittent fasting include feeling cold, tired, irritable, or hungry. You may struggle with these at the start because your body isn’t used to the new fasting schedule. It’s OK to feel uncomfortable, but at no point should things feel unbearable. Try keeping snacks handy, so you can quickly break a fast. Though rare, fasting can decrease blood sugar to an abnormally low level, which can lead you to feel shaky, dizzy, sweaty, confused, or anxious. Feeling unwell in those ways are signs to shorten your fasting period or to stop fasting altogether.
You should also stop fasting if you plan to get pregnant or are underweight, as defined by a body mass index (BMI) below 18.5.
Kudos for your interest in intermittent fasting. If you try it and it works, stick with it. For everyone else, don’t despair because you just learned something new about your body.
Intermittent fasting is just one strategy for weight loss, and research shows that it’s not better than classic calorie restriction. Accept that some individuals do better eating small, frequent meals throughout the day instead of saving up all their calories for one big meal or non-fasting day. You may be one of them.