Intermittent fasting is a hot topic these days, with celebrities touting its benefits. But how does it work? And does it really work? What are its disadvantages?
I answer those questions and more here.
What is intermittent fasting?
Intermittent fasting is a pattern of eating that cycles between fasting and non-fasting over a specific period of time. It's actually been around for centuries, when hunter-gatherers practiced this method involuntarily whenever food was scarce. Since then, our bodies have adapted to be able to function without food, at least temporarily.
Instead of focusing on what to eat, intermittent fasting focuses on when to eat. Because of this, it's considered more of an eating pattern than a diet.
There are three popular methods of intermittent fasting:
- The 16/8 method—by far the most popular—involves eating within an 8-hour timespan and fasting for the other 16 hours; this typically involves skipping breakfast.
- The eat-stop-eat method involves fasting for 24 hours once or twice weekly, usually starting and stopping with dinner.
- The 5:2 method involves eating normally for 5 days and consuming between 500 and 600 calories for 2 nonconsecutive days each week.
Does intermittent fasting work?
Because it involves reducing calories—as long as intermittent fasters don't overcompensate during non-fasting times—it's an effective weight-loss strategy that also naturally increases metabolic rate and cellular repair. Intermittent fasting also helps insulin levels drop and human-growth and fat-burning hormones rise, aiding in weight loss.
But weight loss isn't the only reason for—or benefit of—intermittent fasting. It also can improve:
- Brain health by increasing the brain-derived neurotrophic factor brain hormone, which helps produce new nerve cells, neurons, and synapses
- Heart health by reducing bad, or LDL, cholesterol levels, blood triglycerides, and inflammatory markers that typically lead to heart disease
- Insulin resistance by lowering blood sugar and fasting insulin levels, thereby protecting against type 2 diabetes
In animal studies, it's also been shown to boost energy levels and immunity, as well as reduce markers of inflammation, signs of aging, and potentially even cancer.
What are the downsides to intermittent fasting?
Hunger is an obvious disadvantage to intermittent fasting. It can take time to get used to the feeling, and it can sometimes cause weakness and even brain fog. Typically, these reactions subside after the body acclimates to the new eating pattern.
Women should also be cautious—especially if they are experiencing fertility issues—as some studies have shown intermittent fasting to cause irregular periods. And those with a history of eating disorders should not try this method, as it can trigger past behaviors.
Studying this eating pattern in humans is in its infancy, so there's still a lot to learn about it. But the results so far are promising. If handled properly, intermittent fasting can be an effective weight-loss strategy, with additional healthy perks as well!