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Weight Loss and a Time-Restricted Diet

How time-restricted eating can help you, based on your chronotype.

Key points

  • With a time-restricted diet, you eat within an 8- or 12-hour window which can increase your metabolism and help you lose weight.
  • Your unique biological clock — or, chronotype — determines when you naturally sleep and eat.
  • Time-restricted diets are more effective when you choose a time window that works with your chronotype.

There are plenty of popular diets like the keto diet and paleo diet, and while they have their merits, I personally follow time-restricted eating. But I don’t just limit the hours I eat: For optimal health and sleep, I do it by following my personal chronotype.

Source: deposit-photos

Today I’ll share my tips for following a time-restricted diet whether you’re looking to lose weight, gain energy, or just feel good — and how to do it by following your unique chronotype.

What is time-restricted eating?

Many people confuse time-restricted eating with intermittent fasting, but they are different in two important ways.

First, time-restricted eating requires you to eat according to your circadian rhythm. The idea is that an 8-to-12-hour window gives your digestive system time to rest.

Second, time-restricted eating doesn’t seek to restrict calories the same way intermittent fasting does.

Does time-restricted eating really have health benefits?

You don’t need me to tell you how popular time-restricted eating and intermittent fasting is; it’s hard to go on a health website or log onto social media without at least a mention.

From Hugh Jackman to Jennifer Aniston, celebrities especially claim health benefits. Claims include weight loss, clearer skin, more energy during the day, and less bloating.

Previous studies haven’t backed clearer skin as a health benefit, but have found other benefits, including weight loss and improvements in blood pressure, cholesterol, and blood sugar levels.

But now a 2020 study tells us something more intriguing: How you time your eating window may matter most.

Why does timing matter for time-restricted eating?

Timing is everything — and that may just be the case for getting the most health benefits out of any form of intermittent fasting.

This year, researchers at the University of Alabama studied a sample of obese men diagnosed with prediabetes. The men either ate within an 8-hour period or a 12-hour period. Over 5 weeks, the group that followed the 8-hour window boasted lower blood pressure and insulin levels. They even reported a greater reduction in appetite.

The takeaway? Timing matters when it comes to eating, and may improve metabolism, and even impact how you feel while you’re on a diet.

Why does your chronotype matter for time-restricted eating?

While following a restricted window of eating may be helpful, though, you’ll get the most benefits (including weight loss) by following your chronotype.

The reason no one diet fits all is because we all have unique biological clocks. Your body is essentially programmed to sleep and eat at different times of the day. This internal clock in combination with your chronotype, tells you how to structure your day, from exercise to sleep, and, eating.

If you take on intermittent fasting but are picking a window that goes against your chronotype, not only are you less likely to stick to it, but you also may feel more sluggish and less motivated to exercise. Exercise, of course, is important for maintaining weight loss and healthy blood pressure and sugar levels.

That applies, even if you’re following the more optimal 8-hour eating window.

How to start time-restricted dieting using your chronotype

A quick disclaimer: Intermittent fasting isn’t for everyone, especially for pregnant women and anyone with a history of eating disorders.

If you do want to give a time-restricted diet a try, here’s how you can pair that 8-hour eating window with your natural chronotype to optimize weight loss, productivity, and energy.

If You’re a Dolphin...

Your cortisol levels are lower than others in the mornings, while your body temperature goes down more slowly at night. Begin your day with exercise at 6:30 or 7 a.m.; your eating window for a time-restricted schedule should end by 7 p.m. Your first meal should be a protein-rich breakfast/brunch, with another meal midday, and you should avoid naps. Your dinner should be richer in carbohydrates. Make sure to finish the day without electronics an hour before bed (or use blue light blocking glasses).

If You’re a Lion...

Lions are naturally early risers, with energy peaking in the morning and declining as the day continues. Start with a high protein but low carbohydrate first meal and include a small morning snack of about 25 percent protein and 75 percent carbohydrates. Opt for a balanced lunch, early evening exercise, and finish your day by 6 p.m. with a dinner of equal parts protein, carbs, and healthy fats. A carb-heavy meal like pasta might make you crash.

If You’re a Bear...

Bears, who love socializing and tend to be less consistent with exercise and food, need to be consistent with time-restricted eating. Begin the day with exercise to get cortisol flowing, preferably outside. Your first meal should be high in protein and low in carbohydrates, and your second meal should be half the size. Include a small snack that’s 25 percent protein and 75 percent carbs and finish your eating window by 8 p.m. Take an afternoon nap if you feel you need one.

If You’re a Wolf...

Your first meal should be high in protein, and you should aim to get some sunlight before you reach for coffee. Avoid morning snacks and seek a balanced second meal. A before-dinner snack of 25 percent protein and 75 percent carbs can help you power through an early evening workout. Aim to finish eating by 8 or 9 p.m., with slow-digesting carbohydrates to help you sleep.

I hope this helps and as always: Sleep well!

Dr. Michael Breus

Ph. D, D, ABSM