I always tell my patients, “What you eat matters.” You shouldn’t run a high-performance car on low-quality gasoline — and the same holds true for your body and your diet. But the car analogy only takes you so far. Increasingly, researchers are finding that when we eat may be almost as important as what we eat.
This brings us to the concept of “time-restricted eating,” or TRE, which emphasizes getting most or all of your calories within a more-compressed-than-usual time window, say six to 12 hours (the fewer hours the better) rather than noshing for most of the time you’re awake. (But by all means, drink calorie-free liquids to stay hydrated during ‘fasting’ hours.) TRE also stresses eating your last meal as early as you can practically manage — for example, breakfast at 11 a.m., possible snack at 3 p.m., if necessary, and dinner at 7 p.m. would give you an eating window of eight hours — a TRE starter course!
So why is TRE becoming so popular? The big reason is its positive effect on metabolism as well as on several biomarkers that are important measures of good health. These potentially life-preserving benefits are why I recommend it — and do it myself every day.
TRE helps keep blood sugar in check.
When you graze all day and late into the night, you are messing up your body’s natural rhythms, particularly when it comes to metabolism, including your blood sugar and insulin levels. But with TRE, the shorter eating window syncs up better with your circadian rhythms — the internal clock that regulates your entire physiology, including the sleep/wake cycle. By keeping ‘eating hours’ short, you consume most of your calories earlier in the day when insulin levels are naturally higher and you’re more active. The insulin is able to transport sugar, broken down from the food you eat, out of the bloodstream and into your muscles where it’s burned for energy. That keeps insulin and blood sugar levels stable and healthy versus making your body work overtime dealing with late-night caloric indulgences when it should be sleeping.
TRE can keep weight gain and insulin resistance under control.
When you don’t restrict your feeding hours and eat long into the night, you’re overloading your system with calories when it’s least able to process them. Numerous studies have shown that blood sugar control is at its best in the morning and worst in the evening. In the evening, attuned to your circadian rhythms, insulin levels naturally drop. So when you’re dining at 10 or snacking at midnight, the body has to crank up the insulin machinery again — only this time the muscles likely don’t need any more sugar to burn for energy if you’re lying on the couch binge-watching Netflix. What happens is that those calories get stored as fat, setting the stage for insulin resistance, weight gain, and diabetes. With TRE, however, by restricting feeding hours so you’re done eating by 6 or 7 p.m., your body has plenty of time to burn off calories before it hits the slow-down zone, keeping blood sugar balanced and keeping weight from collecting around your middle. Another bonus of the expanded fasting hours is the increased release of human growth hormone, which can make it easier to burn off stored body fat.
TRE can help keep your gut healthy — and fend off inflammation.
By now, many people understand how important it is to maintain gut health, and interestingly, TRE can be helpful here, too. For example, several studies have indicated that during the fasting portion of the day, the microbes in your microbiome get time off from doing their digestive business to work on repairing the gastrointestinal tract, potentially offering protection from ‘leaky gut’ and, ultimately, the kind of systemic inflammation that can trigger chronic disease. And recently, researchers showed that after each meal, for around four hours, gut microbes and their components leak into our bloodstream – silently triggering inflammation.
TRE can help with autophagy — your body’s cellular recycling and anti-aging program.
In simplest terms, autophagy is your body’s cellular house-cleaning system and your built-in detoxifier. And the healthy stress generated by the fasting periods of TRE can help kick autophagy into high gear as it clears out the cellular garbage — those past-their-prime underperforming cells, infected cells, and cellular toxins. That, in turn, helps protect healthy cells from damage. The added protection can help tame inflammation, enhance neurological health and slow the aging process, increasing both healthspan and lifespan.
TRE can help you see eating in a different light.
When you embrace time-restricted eating, the physiological benefits mentioned above are major wins for your health, in both the short- and long-term. But, don’t forget, there are also a number of psychological bonuses as well, with one of them being the development of a new relationship with food. For many people, TRE can be helpful in gaining a sense of control over food intake, without feeling deprived or compromising their nutritional needs. For others, without those late-night noshes interfering with their circadian rhythms, it becomes easier to turn in a bit earlier at night and fall asleep more naturally. Another plus? You can do TRE as often as you like, be it a few days a week, every day, or whatever works with your schedule, so even though TRE restricts feeding hours, it still provides plenty of flexibility.