Time-Restricted Eating: Benefits, Risks & How To Tailor It To Your Lifestyle

Time-restricted eating (TRE) is one of the few eating patterns that doesn't have any complicated rules or regulations to remember and allows you to enjoy all your favorite foods, provided you fit all of your meals into an allotted time slot.

In addition to the flexibility and freedom that this plan offers, TRE also touts a long list of possible health benefits, ranging from increased longevity to weight loss, improved blood sugar control, and more.

Time-restricted eating is a form of intermittent fasting that involves limiting your food intake to a specific window of time each day.

In most cases, people will limit their food intake to a six- to 12-hour slot and fast during the remaining hours outside of this time period. Though some people limit their intake during fasting periods to water only, others may choose to opt for calorie-free beverages, like black coffee or tea, or eat a small number of calories.

In recent years, TRE has soared in popularity thanks to the unique flexibility that it offers. Contrary to other diet plans that focus on meticulously measuring grams of carbs, fat, or protein, TRE doesn't require you to log your food intake and enables you to eat whatever you choose within a specific time period each day.

According to Humaira Jamshed, Ph.D., a researcher and assistant professor at the Dhanani School of Science and Engineering, TRE has been shown to promote cellular repair1 and autophagy, a process in which the body breaks down damaged cells and replaces them with healthy new cells.

"Research suggests that autophagy2 may have a protective effect against aging, cancer, and other diseases," says Jamshed.

In one study conducted by Jamshed and her colleagues, participants followed an early time-restricted eating plan for four days, which involved limiting their food intake to the hours of 8 a.m. to 2 p.m. each day. By the end of the study, researchers observed increased markers of autophagy1, suggesting that TRE could potentially have anti-aging effects.

"TRE may be promising for people who have struggled with weight loss or calorie counting in the past," explains Kelsey Gabel, R.D., Ph.D., an assistant professor and intermittent fasting researcher at the University of Illinois at Chicago.

"From the current data, it appears that people naturally restrict calories4 by about 20% when eating in a shorter window every day. This seems to result in somewhere between a 2- to 4% weight loss in two to three months without counting calories," says Gabel.

While it may sound too good to be true, this found in a 2018 pilot study4 conducted by Gabel and other researchers. The study found that, on average, people who limited their food intake to an eight-hour period each day consumed 341 calories less per day and lost 2.6% of their body weight over a 12-week period.

In addition to supporting weight loss, TRE may promote other aspects of metabolic health as well. "TRE is currently being explored for blood sugar regulation in individuals with prediabetes and even Type 2 diabetes," says Gabel.

Jamshed adds that it may help reduce insulin resistance6 and increase insulin sensitivity, which can improve your body's ability to use insulin to regulate blood sugar levels effectively.

Early TRE usually restricts food intake to a period earlier in the day and involves fasting in the early afternoon.

Sticking to an early eating schedule may help you get the most bang for your buck, according to Jamshed.

"This method helps correct circadian misalignments7, and eating in sync with the external cues of daylight helps improve health," says Jamshed, who also notes that it may be the most effective option for improving metabolic health, weight loss, mood, and sleep.

This is also reflected in multiple studies, which have linked an early time-restricted eating schedule to improved insulin sensitivity8, decreased oxidative stress8, increased weight loss9, and reduced blood pressure levels9.

However, this plan may be challenging to stick to, especially as it involves forgoing family dinners, happy hours, and late-night snacks. It might also not be a good fit if you sleep in or prefer eating your morning meal a bit later in the day.

Midday TRE involves limiting your food intake to the middle of the day, often by skipping breakfast and eating an early lunch.

"This approach may be more practical for those with work schedules that require a midday meal and may still offer some of the potential benefits of early TRE," says Jamshed.

However, it may not align with your natural circadian rhythms as well as early TRE, she says, which could diminish some of the possible benefits. In fact, one study comparing the two methods found that early TRE was more effective at improving insulin sensitivity10 than midday TRE.

Early TRE was also associated with reductions in body weight, fasting blood sugar levels, and inflammation, whereas midday TRE was not.

Late TRE generally requires you to skip breakfast and eat a late lunch.

Jamshed states that this could be a good option for people who prefer to socialize or eat dinner later in the day, noting that it may still offer some of the benefits of TRE.

In fact, a recent trial11 comparing early and late TRE found that both resulted in similar amounts of weight loss compared to a control group. However, early TRE still had an edge over late eating, especially in terms of its effects on blood sugar, blood pressure, fasting insulin, and insulin resistance.

According to Jamshed, late TRE may not be ideal for blood sugar control and fat burning, as our body's sensitivity to insulin tends to decline12 in the evening. "Additionally, eating close to bedtime may disrupt sleep quality for some individuals," she says.

"Placing the eating window earlier in the morning (finishing the eight-hour window by 2 or 3 p.m.) may have more benefits for glucose control," says Gabel. Jamshed agrees, noting that early TRE may be the most effective option when it comes to metabolic health, weight loss, and mood.

However, both also acknowledge that this eating pattern may be harder for some people to follow, as many people prefer socializing in the evenings and enjoying dinner with family or friends.

Jamshed emphasizes that there's no single "best" type of TRE for everyone, as the most appropriate option can vary depending on many individual factors. "It's important to choose a TRE method that is sustainable and enjoyable, and to speak with a health care professional before starting any new dietary or lifestyle regimen," she says.

Ultimately, it may be best to tailor your eating pattern to your individual schedule and experiment with the precise timing to find what works for you.

And as far as how long to fast, if you're new to time-restricted eating, consider checking out 18:6 and 16:8 fasting plans, both of which involve abstaining from food for 18 or 16 hours each day, respectively.

Though TRE may offer several possible health benefits, it's not a good fit for everyone. Gabel states that intermittent fasting in general is not recommended for children, adolescents, people with a history of eating disorders, and those who are underweight.

Additionally, she notes that there is limited research on the safety of fasting for other groups, including people who are pregnant or lactating and individuals over the age of 70.

Time-restricted eating is a flexible eating pattern that may offer benefits in the long run, including increased weight loss and improved metabolic health. Additionally, there are several variations available, making it easy to incorporate TRE into your schedule.