Intermittent Fasting for Weight Loss
What is intermittent fasting?
Intermittent fasting is not a diet. It is a pattern of eating with intermittent periods of fasting and feasting. It limits when you eat and not what you eat, which eliminates the need to count calories while still losing weight.
Some believe that it’s a more natural way of eating because humans evolved without refrigerators or having 24-hour convince stores. Modern day humans have access to food (including junk food) all day long, so eating several meals per day plus snacks may be less natural than fasting from time to time.
Most popular methods of intermittent fasting include:
- Eat-Stop-Eat which involves fasting for 24 hours, once or twice a week by not eating from dinner of one day until dinner of the next day.
- 16/8 which is 16 hours of fasting followed by eating only within an 8 hour window (often 1:00 pm. – 9:00 p.m.);
- 5:2 days of fasting, where you eat regularly for five days of the week, then take in just 500-600 calories/day for the other two (non-consecutive)
When starting out, choose one day of the week when demand on your energy is low. For example, you can fast once a week for 16 hours and consume 2 meals (no snacking) in an 8 hour window (eg. fast between 9pm Friday night until 1 pm on Saturday). During fasting phase, you may consume water, tea and coffee without milk or cream, broth, apple cider vinegar.
How intermittent fasting can help with weight loss
Intermittent fasting helps with weight loss because it restricts caloric intake. It also helps you lose that pesky abdominal fat. According to one review study, intermittent fasting helped people to lose 3-8% of their weight over 3-24 weeks. In this study, people also lost 4-7% of their waist circumference (i.e., belly fat).
Another study of 100 people with obesity showed that after a year, people who fasted on alternate days lost more weight than people who didn’t change their eating pattern. But they didn’t lose more weight than those on a calorie restricted diet. Out of the people who followed intermittent fasting protocol, 38% of them dropped out. Sticking with a diet is one of the keys to weight loss success. So, if you can’t stick with intermittent fasting, you’re less likely to lose the weight and keep it off.
Risks of intermittent fasting
Before you jump into intermittent fasting, here’s what you should keep in mind. If you are underweight, or have eating disorders you shouldn’t fast. Neither should women who are pregnant, trying to get pregnant, or are breastfeeding. Certain medical conditions can be worsened with longer periods of fasting. Also, people taking certain medications may be prone to side effects with intermittent fasting as well.
Risks of intermittent fasting include fatigue and low blood sugar level symptoms such as shakiness, dizziness, sweating, hunger, irritability or moodiness, anxiety or nervousness and headaches.
One of the reasons people quit intermittent fasting is that it’s hard to stick with the fasting part. They eat more than the allowed (low-level of) calories when they’re supposed to be fasting. And when they finish fasting, they may overindulge due to the reaction of the appetite hormones and hunger drive while fasting. None of these will help with weight loss.
Also, the hours and days of fasting can be very difficult. So having strong social support is key to successful intermittent periods of fasting. Sticking to a (healthy, nutrient-dense) weight loss diet is the crucial to success, and intermittent fasting can be difficult for many people to stick with.
Intermittent fasting is a weight loss trend that seems to work for some people. It can help to lose weight and reduce belly fat. But, it isn’t safe for everyone.
Always speak with your healthcare provider before making changes to your diet.
For best outcomes of long-term weight loss success, finding a diet, you can stick with is key.
You can start finding answers to your diet and weight loss questions by scheduling a complementary discovery session HERE. We will go over your goals and review treatment options available to you.
Dr. Anna ND
- Harris, L. Hamilton, S. Azevedo, L. B. Olajide, O. J. De Brún, C. Waller, G. Whittaker, V. J. Sharp, T. Lean, M. Hankey, C. Ells, L. Intermittent fasting interventions for the treatment of overweight and obesity in adults aged 18 years and over: a systematic review and meta-analysis.JBI Database of Systematic Reviews and Implementation Reports:
- Intermittent fasting: Surprising update. https://www.health.harvard.edu/blog/intermittent-fasting-surprising-update-2018062914156
- Not so fast: Pros and cons of the newest diet trend. https://www.health.harvard.edu/heart-health/not-so-fast-pros-and-cons-of-the-newest-diet-trend
- Intermittent Fasting 101 — The Ultimate Beginner’s Guide. https://authoritynutrition.com/intermittent-fasting-guide/