Home > Food & Nutrition > Starting a New Diet? Try Intermittent Fasting
“I skipped breakfast today.” “I’m going to skip lunch today!” You may have heard your friend or coworker say something like this. You might even ask them: “Won’t you feel very hungry?” They may reply that they are doing this to lose weight after indulging in rich meals during the holidays. After all, isn’t it true that eating less every day will naturally help you become healthier and slimmer? Yet, because humans find it difficult to function without eating for long periods of time, losing weight all depends on the timing of the fast.
Are you interested in jumping on this trend? Read on to learn more about intermittent fasting and whether it is suitable for you.
What is it?
Intermittent fasting (IF) has become popular for weight control and improving health such as disease prevention, cellular repair, and better insulin sensitivity. IF is eating within a restricted time frame. The time frame can vary depending on the type of intermittent fasting such as alternate day fasting, periodic fasting, and time restricted eating.
- Alternate-day fasting: The protocol is to fast every other day following a 24-hour window.
- Modified alternate-day fasting: The protocol is to eat no more than 500 kcal every other day.
- The 5:2 diet: The protocol is to eat no more than 500-600 kcal two days per week non-consecutively.
- Time-restricted eating: The protocol is to eat within a restricted daily time frame that can vary depending on the preferred time. A popular method is 16:18 that requires 16 hours of fasting and 8 hours of eating within a 24-hour period. An example is to eat between 9:00am-5:00pm or 11:00am-7:00pm.
Credit: Getty Images
- Consume healthy foods and avoid snacking: There are no food restrictions, but it is important to eat a diet rich in whole foods and low in processed foods, salt, saturated fat, and sugar for the best functioning body and good health. Remember that eating healthy is more than about achieving a weight goal!
- Consume satiating foods: Protein and fiber will help maintain a feeling of fullness during the fasting period. These nutrients can be found in fruits and vegetables.
- Eat the right amount of kcal: There are no specific calorie recommendations, but not eating enough can lead to a lower metabolic rate while eating too much can cause weight gain. You can try exercising portion control, such as putting food on a smaller plate or bowl to reduce your intake.
- Stay hydrated: Drink enough water and stay hydrated according to physical activity. It is also recommended to drink before eating to reduce hunger pangs and control your portions.
- Plan eating around exercise: Eat around the time of exercise to fuel for the task whether you need carbs for vigorous exercise lasting more than 1-1.5 hours or protein to build muscle.
Most human studies tend to be small or short-term, so more robust observational studies and randomized controlled trials are needed to fully understand the role of IF in weight loss and disease protection. Time restricted eating is the type of IF most supported by research and therefore, most likely to have a positive effect combined with a healthy diet. Below are some of the potentials IF benefits (the research presented is not comprehensive):
Weight loss: A systematic review of 27 IF trials that included 18 small randomized controlled trials (RTC) and 8 trails with no control group found a weight loss of between 0.8%-13.0% of baseline weight with no serious adverse events. It is important to consider if the IF groups outperformed the control groups when reviewing studies. A 12-week 2020 RTC observed a 7% body fat decrease in both the IF group and continuous calorie restriction group. A 1-year 2018 RTC observed a weight loss of 8.0 kg in the IF group versus 9.0 kg in the continuous restricted calorie group at 6 months and a similar between group weight maintenance after an additional 6 months.
Improved insulin sensitivity: A 6-month RTC found that IF decreased fasting insulin by 23% and HOMA-IR (homeostatic model assessment of insulin resistance) by 29% in post-menopausal women. This means that your cells become more responsive to insulin and can help you control your blood sugar levels.
Heart Health: A 2018 12-week pilot study with 23 participants found that an 8 hour IF window may lower blood pressure (–7 ± 2 mm Hg). After a systematic literature review of PubMed, the American Heart Association found that, IF may decrease triglyceride concentrations by 16%- 42%. Triglycerides are a type of fat found in your blood that has been converted from unused calories and through IF, you may be able to get your triglycerides within the normal range. This may help reduce heart disease.
IF is not ideal for everyone- what you should consider before adopting this diet
A narrow eating window may interfere with social gatherings or family mealtime. The first few weeks of IF can make you feel cranky because you are used to eating more times every day. It may also be more beneficial for men than women due to hormone differences. It is recommended to consult a medical professional and take careful consideration if you have a medical condition or in one of the following groups.
- Trying to conceive or undergoing fertility treatments
- Diabetic or issues with blood sugar regulation
- History of an eating disorder(s), eg. anorexia or bulimia
- Take medication
- Have low pressure / hypertension
- Amenorrhea / irregular period
Other Healthy Eating Habits
IF may be a good alternative option to continuous calorie restriction for weight loss and improved health. Whether or not IF is right for you, here are some safe and easy meal timing strategies to follow:
- Eat breakfast: It may be ideal to shift the bulk of calorie consumption to earlier in the day due to our cycadean rhythms. Eating breakfast could allow for extra calorie consumption without added weight and provide energy for a morning workout. Consider swapping the morning coffee for healthy plant-based foods to keep energized and avoided sugary processed food if possible.
- Eat a Modest Dinner Early: Late eating can interfere with our cycadean rhythms. Try to eat dinner by 6-7 pm and don’t eat right before you go to bed. You have to give your body time to digest your meals.
- Don’t drink alcohol before bed: This can also interfere with our sleep- lack of sleep leads to weight gain.