How your body's rhythm could help you lose weight, sleep better and live longer

A new book advocates a lifestyle change based around our circadian rhythms to improve our health, beginning with when to eat, when to sleep, and when to get some exercise, writes Karen Murray.

LOSE weight, become more energetic and sleep well every night. Bold promises outlined on the cover of The Circadian Code. Another fad diet where you eat nothing but tomatoes and broccoli and have to run 10 miles a day? No, not even close.

The term circadian is derived from the Latin ‘circa diem’, meaning ‘approximately a day’. This isn’t a diet, it’s a lifestyle change and one that involves relatively small adjustments to daily routines. It begins with knowing when to eat (as opposed to what) and when to turn off the lights, exercise, maximise sleep and brain function. Sounds simple? Author Dr Satchin Panda seems to think so.

If you’ve ever noticed that you tend to feel energised and drowsy around the same times every day, you have your circadian rhythm to thank. This 24-hour internal clock is running in the background of your brain. It’s also known as your sleep/wake cycle or a ‘body clock’, a cycle that tells our bodies when to sleep, rise and eat.

Dr Satchin Panda

Dr Panda, Professor at the Salk Institute for Biological Sciences in San Diego, California — which consistently ranks among the top institutions in the US in terms of research output and quality in the life sciences — is a leading expert in the field. He says that choosing when we eat, sleep, exercise and work is more crucial to our well-being than previous research indicated. And, more importantly, if our daily schedule is out of sync with our circadian rhythms, it can easily be fixed.

“Our circadian codes rise and fall at specific times of the day,” Dr Panda explains. “But in modern society, there’s a lot of disruption, particularly, for example, if you are a shift worker or a new parent or have jet lag for example.”

While we can’t go back to how our ancestors lived, we can adapt our often chaotic lifestyles. Dr Panda’s lab discovered that confining calorie consumption — Time Restricted Eating (TRE) — and, yes, that includes the cuppa and biscuit or glass of wine, to an eight- to 12-hour period (ideally 10 hours) may help to stave off conditions like high cholesterol, diabetes and obesity.

Research shows that TRE also has a positive impact on depression, anxiety, gut problems and insomnia, thereby reducing the need for sleeping tablets or anti-acid medication.

Three primary factors disrupt our circadian codes, he says — eating habits; not enough light during the day and too much at night, and not enough sleep. Because of these factors, our craving for food increases and we tend to eat (and drink) at the wrong time, binge on unhealthy options and are less likely to go out for a walk or take any exercise.

This has an impact, not just on our weight and our sleep patterns, but on our general well-being and longevity. Using the circadian clock, each organ is programmed to process food for a few hours starting from breakfast. So if that’s at 8am, the system works optimally for eight to ten hours. Every morsel we eat takes time to digest, absorb and metabolise. After the eight- or 10-hour period, the gut and metabolic organs will continue to work on food but their efficiency slowly goes down.

“Eating should take place ideally in a 10-hour window,” Dr Panda explains. “How we choose our 10 hours depends on our work routine, but we should do all our eating within that time.

“If we wake up with an alarm clock, we should wait an hour to eat and drink anything and we should stop all food and drink at least two to three hours before we go to bed.”

So, for example: On an ideal day, you would finish dinner around 7pm and go to bed at 10.30pm (no food or drink in that period). Then rise at 7am and have breakfast at 8am. And what about shift or night workers? They can reverse the hours and still adhere to a TRE schedule, Dr Panda says. As long as you eat an hour after rising, and stop two to three hours before going to sleep, the principle remains the same.

In fact, he has worked with police officers and firefighters in San Diego to allow them to align their hectic work schedules around their circadian rhythms.

Obviously, routines vary. We travel, work late, have a late meal with friends ... but we can still adhere to the principles.

“If you eat a late dinner, try to give your stomach at least 12 or 13 hours before the next meal. If you sleep late, try to exercise the next day. We are shooting for perfection but sometimes good enough has to do,” he says.

Dr Panda explains that the research began with a simple experiment in 2009 feeding mice, which are normally nocturnal, during daytime hours only. Further research in 2012 revealed that restricting the hours in which the mice ate protected them from obesity, diabetes, heart and liver disease compared to mice who ate the same foods, with the same calories, but over a longer period.

Dr Panda believes most diseases that affect us in adulthood (high cholesterol, obesity, diabetes, even cancer) can be traced back to circadian disruption. He is not a medical doctor and cannot prescribe medications to treat chronic illnesses, but he believes that many of these can be prevented by taking small changes to our daily routines and that billions can be saved in the health service each year as a result.

“A third of adults in the US have one or more chronic diseases and in the mid-40s this rises to two out of every three people,” he says. This field of research is not driven by a goal of curing disease, but preventing it from happening, or at least delaying it by 10 years.”

Boost your circadian rhythms

  • Where possible, stick to a 10-hour eating window.
  • Wait an hour before you eat or drink anything other than water in the morning and do not eat or drink anything for at least two or three hours before bed.
  • Get as much natural light during the day as possible. At work, try to break up your day with a short walk outdoors, even standing and stretching every hour.
  • Physical activity is vital: Even the busiest people can find 20 minutes for a walk.
  • Dim the lights in the evening at home.
  • Be aware of room temperature. Many people wake up during the night because they are too warm.
  • Eat proper, nourishing foods. It’s when you eat, rather than what you eat, but don’t pig out on doughnuts. Avoid processed foods, where possible.
  • Remember that coffee can stay in your system for 10 hours, so try to avoid it after midday.
  • Chart your routines — how often you wake at night, when you feel hungry, what are the triggers, and see if you can make changes.
  • - The Circadian Code by Dr Satchin Panda is available on paperback or ebook (€14.99 RRP). Published by Penguin Books


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