There’s a lot of hype around intermittent fasting—and a lot of questions about it, too. Intermittent fasting consists of intervals of fasting during which you abstain from eating for a designated period of time, leading your body to switch from burning sugar as fuel to burning body fat as fuel. It is a tool used by many to aid in weight loss and increase lean muscle mass.
There is a wide variety of intermittent fasting protocols, ranging from short daily fasts to periodic long fasts. The most common form of fasting consists of setting a daily eating window between 8 and 12 hours followed by a 12- to 16-hour fast. Other protocols include a 4-hour eating window daily, 24-hour fasts twice weekly, alternate day fasting, random fasting and long periods of fasts once a week or month.
While many people claim one form of fasting to be more effective than others, no substantial studies have been done to prove which style is most beneficial. And despite the hype, intermittent fasting is not required to successfully lose weight.
How does intermittent fasting promote weight loss?
Your body has two ways of storing food as energy. It can either be stored as glucose (sugar) in the form of glycogen, or it can be stored as fat. The body has very limited storage for glycogen; when your body reaches its capacity, the leftovers get stored as body fat, which has unlimited storage.
Generally, you are constantly pulling from your carbohydrate stores for energy. When these stores become depleted, you typically just eat more food rather than dipping into your fat storage for energy.
But when your need for energy increases and you refrain from consuming more food, you boost the production of hormones that allow you to burn your body fat for energy. Growth hormones, noradrenaline, adrenaline and cortisol are released, naturally increasing your blood sugar and giving you energy without the need to consume more food. These hormones also encourage your body to break down fat tissue and mobilize them for the use of energy.
Intermittent fasting works to deplete your glucose storage and dive into body fat for energy, rather than intaking more food. In simpler terms, eating shuts down the fat-burning process–and taking a break from eating allows your body to eat breakfast, lunch or dinner on its own body fat.
What can you consume when fasting?
Intermittent fasting protocols allow you to drink water, tea and black coffee, as well as supplement with essential amino acids and electrolytes. Some protocols are less strict, allowing you to drink Bulletproof coffee and bone broth during your fasts. These “rules” generally apply to shorter, daily fasts.
When doing longer fasts, such as a 24-hour fast, certain protocols allow women to consume 500 calories and 600 calories for men. These parameters are acceptable as long as the calories come from foods that do not spike your insulin (i.e., no carbohydrates, sugar or processed foods), small portions of lean protein, eggs or protein powder, non-starchy vegetables (mostly dark leafy greens) and unprocessed fats.
Many doctors recommend not overthinking it. If adding a tablespoon of creamer or milk to your coffee helps with adherence, then do it. They believe it to still be more productive than eating a full meal.
Who should try intermittent fasting?
Current studies show you can gain the same benefits of intermittent fasting through a controlled diet. All intermittent fasting protocols encourage you to avoid snacking, consolidate your calories at the end of the day and focus on eating unprocessed, whole foods, which can all be done without adopting an intermittent fasting diet. Controlling your calorie intake (which does not mean drastically restricting calories), eating a diet low in processed foods, chemicals and pollutants, regular exercise and avoiding foods that raise blood sugar and release insulin can match the benefits of intermittent fasting.
While intermittent fasting is widely accepted as safe for men, doctors tend to have varying opinions on its safety for women.
If intermittent fasting is not done correctly, it can cause hormonal imbalances in women. Estrogen levels are greatly affected, and as women have estrogen receptors located throughout the entire body, it can mean more than just missed or lost periods. When estrogen levels are abnormal, your mood, digestion, muscle recovery and growth can also be affected. It may lead to hunger hormones being thrown off balance, too, causing increased appetite and food cravings.
For women who want to try intermittent fasting, fasting for 12 hours followed by a 12-hour eating window is widely recommended by healthcare professionals. Longer fasts have shown to cause negative health effects. Remember: Each person is different, and it is best to experiment with what works best for you.
Who should not try intermittent fasting?
Intermittent fasting is often used as a cover-up for eating disorders and may not be for you if:
- You have exercise addiction and regularly over-exercise
- You use intermittent fasting as an excuse to not eat
- You depend on appetite-suppressing supplements
- You are food-obsessed and/or binge during non-fasting periods
- You use intermittent fasting as a way to “compensate” for poor food choices or overeating
Intermittent fasting may also not be for you if:
- You do not get enough sleep or are under high stress
- You are pregnant
- You are new to eating a healthy diet and regular exercise
- Your menstrual cycle stops or becomes irregular
Stop intermittent fasting if you develop the follow symptoms:
- You develop dry skin or acne
- You regularly experience low energy levels
- You have slow muscle recovery
- Your injuries are slow to heal
- You get sick easily and often
- Your stress levels increase
- You experience mood swings
- Your heart beats irregularly
- Your digestion slows
- You always feel cold
- You experience regular constipation
Tips and Considerations for Intermittent Fasting:
1. Prior to adopting an intermittent fasting diet, get the nutritional basics down first. Eat good quality food, in the right amounts, at the right times. For most people, this is enough to see amazing results, without the need to fast.
2. All styles of intermittent fasting focus on consuming whole foods during periods of eating and do not include binge-eating when breaking the fast. If you find intermittent fasting triggers a binge-eating session post-fast, this style of eating is not right for you.
3. Monitor and control your calorie intake before beginning intermittent fasting. Many people who do not have control of their calorie intake will overeat when breaking their fast, leading to weight gain.
4. Have a plan of what you will eat when you break your fast. Ensure you have nourishing whole foods readily available, preventing you from overeating and helping you replenish your body properly.
5. Start with a short fast and slowly increase its length by one hour each week. If you generally snack at night, try beginning by eliminating late-night eating. The next step would be to eat breakfast one hour later or dinner one hour earlier. Continue to do so until your desired eating window is reached.
6. There are many different styles of intermittent fasting; it is not one-size-fits-all. Determine which protocol is best for you by setting a goal, taking initial measurements and reassessing after 14 days to see whether it is working for you or not.
7. Extended fasts may be harmful to your fitness goals. If you are performing vigorous exercise, break your fast and intake the majority of your calories directly afterward. Make sure you eat nutrient-dense foods post-workout to help your muscles recover and build and restore carbohydrate stores.
8. If you’re doing fasted exercise, it is beneficial to supplement with 10 grams of branch chain amino acids (BCAA) beforehand.
9. Skipping breakfast does not mean drastically reducing your daily caloric intake. Within your eating window, you will still consume the amount of calories your body needs to function optimally. If you constantly feel cold during intermittent fasting, this is a sign you need to consume more calories within your eating window.
10. If intermittent fasting causes constipation, increase your fiber intake. Adding organic powdered greens to a protein shake is an easy way to increase fiber intake. Try senna tea or magnesium (like a Natural Calm tea magnesium supplement) before bed.
This information is not intended to be a substitute for professional nutrition advice. Please seek the advice of a healthcare professional before undertaking a new healthcare regimen.