You or someone you know have probably heard the term “intermittent fasting” in the past few months, one of the latest health and fitness trends taking the world by storm.
So, what is intermittent fasting?
Intermittent fasting (IF) is a term for an eating pattern that cycles between periods of fasting and eating. It doesn’t necessarily dictate which foods you should or shouldn’t eat, but rather when foods should be eaten. Some studies show that eating patterns (fasting) that eliminate nighttime snacking can result in health improvements for sleep patterns, microorganisms that aid in digestion, and biomarkers (glucose, insulin, lipids, inflammatory markers).
Sounds great, right?! Maybe, there’s more to consider.
Fasting can be considered different than dieting because it’s more of an eating “pattern.” Common IF methods involve going 12-18 hours a day without food – or sometimes fasting for 24 hours twice per week.
Some studies show that IF can help you lose weight, improve blood sugar levels and insulin sensitivity, in addition to having heart-healthy benefits. However, when IF is compared to what you would consider your typical calorie-restricted diet (eating fewer calories per day, perhaps by practicing portion control or omitting certain foods) – identical results can be achieved!
One study looked at biomarkers in those who participated in IF vs. those you participated in a calorie-restricted diet; they found that both groups had comparable reductions in leptin, inflammatory markers, cholesterol, triglycerides, and blood pressure. Additionally, recent studies show that IF does not produce superior adherence, weight loss, weight maintenance or heart health vs. daily calorie restriction. Studies are showing that IF may be an equivalent alternative to a typical calorie-restricted diet.
Before jumping on the IF bandwagon, you may want to ask yourself a few questions:
- Is IF feasible and sustainable for me and my lifestyle? My job?
- Based on any medical condition(s), is it wise to go so many hours or even days without food?
- What can I maintain long-term to continue seeing these benefits?
Is it for me?
IF is not for everyone, and those with diabetes should proceed with caution. A recent study conducted in New Zealand compared 2 groups of individuals with diabetes: one group fasting for 2 consecutive days, the other group fasting for 2 non-consecutive days, each week. Their study determined that during fasting, regardless of which type, the risk of a hypoglycemic event doubled, despite a reduction in medication. Both groups did, however, report improvements in hemoglobin A1c, weight, and quality of life. We also know that these same results can be achieved with your typical calorie-restricted diet, and have known this for many years.
The main reason IF works is that it helps you eat fewer calories overall. For example, if you are fasting for 14 hours per day, let’s say from 7 pm to 9 am, you are eliminating late-night snacking on, likely, high-calorie foods like chips, ice cream, cookies, etc. Or perhaps you are conscious about fasting between meals, meaning you’re probably omitting any treats from the office candy jar or forgoing your afternoon soda habit. IF is just another method of restricting daily calorie intake.
However, another aspect to consider is how likely you are to binge and eat massive amounts during feeding periods, because then you may not lose any weight at all. With the temptation to over-eat from being so hungry, it’s possible you could even gain weight on this meal pattern.
Though IF can be effective, similar results can be achieved with general calorie-restriction in regards to overall health, weight loss, and improvements in biomarkers. To date, no long-term randomized clinical trials have evaluated the efficacy of IF. In fact, one study showed those who were part of the IF group indicated they were less likely to maintain that lifestyle long-term, as compared to the calorie-restricted diet group.
While IF may be effective in jump-starting your weight loss goals, you must also consider what you are going to be able to maintain long-term if you wish to continue seeing results.