A calorie is a calorie is a calorie…so WHEN you eat shouldn’t matter, right? You’re not alone if you’re still thinking that.
But, a growing body of research is demonstrating that not paying attention to when you eat can hurt your weight, health, and energy level.
This article will explain why WHEN you eat matters. More importantly, you’ll learn how to get healthier and feel more energized – not by eating less, but simply by changing WHEN you eat.
Much of the “why” behind the idea that when you eat matters can be explained by understanding our circadian rhythm.
Because we live on a planet that makes one complete rotation on its axis every 24 hours, it’s easy to assume that we’ve conveniently adapted to this environment by sleeping at night and waking up in the morning.
Yet humans left in a windowless environment without clocks and allowed to eat and sleep as desired naturally adapt to a nearly 24-hour cycle of sleeping and waking, referred to as a circadian rhythm.
Our circadian rhythm is controlled by the master clock in the hypothalamus of the brain as well as internal clocks within each organ of the body.
This internal clock doesn’t just affect waking/sleeping…many of our body functions align with this genetically programmed 24-hour cycle. For example, during the day, we produce more insulin to lower our blood glucose – and less when the sun goes down.
That’s why the same exact meal tends to produce higher blood glucose levels when eaten in the evening, than in the morning – we are not producing as much insulin at that time of the day.
As the sun goes down, our body produces melatonin to make us sleepy – and growth hormone to heal our body during sleep. No wonder sleep deprivation can result in more illness.
Recent studies have shown that when we mess with this cycle – for example, by working into the wee hours or eating late in the evening or during the night – we tend to gain more weight. It also might hurt our health.
Many of my clients, especially those that work past 5PM, ask, “How late is too late to eat dinner? When should I stop eating?”
My answer is always, “The earlier the better.” This research article summarized a couple of randomized controlled trials that support early eating:
The studies suggest that it’s best to honor your circadian rhythm and eat during the daylight hours and not eat at night.
But it’s not just about when to shut down the kitchen, it might help to assess what time of the day you are eating the majority of your food. Is it during breakfast and lunch – or is it during the evening dinner meal?
A large study in Spain suggests that our body is often suited to eat more early in the day – and less in the evening hours. In this study, 420 overweight and obese women followed a 1400 calorie diet that varied only by WHEN the calories were eaten. One group ate more calories early in the day:
The other group ate the same number of calories but they were given a larger dinner (and a smaller breakfast):
Even though both groups were eating the same number of calories, the group eating the larger breakfast showed greater weight loss and waist circumference reduction.
They also reported lower hunger scores and higher satiety scores. In addition, fasting glucose and insulin levels fell more. And, triglyceride levels only fell in the breakfast group – they went up in the dinner group.
While the study did not test energy levels, better health is likely to coincide with better energy.
Over my years of coaching clients with health and weight issues, I’ve met many individuals who eat very little or nothing during the day. Unfortunately, they then MORE THAN make up for it in the evening hours. Sometimes that schedule is just a habit of theirs.
Oftentimes the client reports that they feel hungry but they ignore their hunger signals. They’re worried that if they give into the hunger it will result in overeating.
I get it. I used to think that way, too. But, hunger is a body signal that food is required and should not be ignored. You don’t ignore the urge to go to the bathroom, do you?
To improve their health and weight, for many it’s a (relatively) simple matter of helping them to understand that our body works best to fuel up earlier in the day. And, that eating more during the day can increase satiety and prevent excessive hunger during the evening hours.
For the switch to occur, I help people get back in touch with their hunger signals so that they’re ready to eat earlier in the day. I also help them get into a breakfast habit. If not breakfast, or at least start eating earlier than usual. If the first meal is lunch, then I might suggest a snack at 10 or 11AM. (Let me know if you’re looking for a health coach. You can find out more about my services HERE.)
Sometimes clients present more symptoms than can be explained by ignoring their hunger or bad habits. I refer them to a mental health professional. Only 1.5% of the population has Nighttime Eating Syndrome, but it’s far more prevalent in the obese population.
The Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-V) includes these criteria for Nighttime Eating Syndrome:
Treatment for Nighttime Eating Syndrome include pharmacologic treatment, cognitive-behavioral therapy (CBT), and light therapy. Not only can these treatments help to develop healthier eating habits, they can improve mood and lower weight.
So, just because the light comes on in your refrigerator when you open it, doesn't mean you should be eating at night.