Could Eating Carbs At Night Make You Lean?

I hear a lot of dieters saying you should never eat late at night.

Carbs in particular are often highlighted, as if they somehow take on a magically different structure once the clock strikes a certain time.

I often find myself wondering where these ideas come from in the first place.

I mean, it’s important to question if there’s any science to back up the notions we have about dieting, or if they are merely anecdotes.

I’m not against anecdotal evidence completely, but things get a bit rocky if that’s all you’re relying on.

I suppose there are many things in the diet-world that have become accepted as fact, when in reality they are nothing more than theories, that have been repeated loudly enough so people eventually start believing them to be true.

And, there are a lot of theories about carbs floating around these days. As I discussed recently, it can get super confusing at times.

So, is there any truth to the idea that eating carbs at night makes you fat, fast?

Carbs At Night

Anger managementWell, there is a theory that metabolism slows down at night.

So, when you eat high carb foods later on, there’s a greater chance they will be stored as fat, compared to eating carbs earlier in the day, where there is more chance they would have been burned off.

Sounds reasonable — you lie down, you move little, you burn fewer calories, right?

But, while that appears to make some sense…

The research shows it’s more complicated than that;

  • Energy expenditure decreased during the first half of sleep by around 35 percent. But, during the latter half of sleep, it significantly increased, associated with REM sleep.
  • This seems to be inline with resting metabolic rate (RMR), which also rises and falls throughout the day.
  • However, in another study, obese individuals had sleeping metabolic rates lower than their resting metabolic rates, whereas lean subjects had sleeping metabolic rates significantly higher than their resting metabolic rate.
  • From all of this, we can gather that metabolism actually increases while you sleep, unless you are obese.
So, as you can see, the theory that eating carbs at night makes you fat because metabolism slows down, doesn’t really stand up to testing. We cannot completely write it off as a possibility, but I wouldn’t call this a very strong argument.

“Carb Back-Loading”

In fact, there’s an interesting school of thought that eating most of our carbs at night, could help us get, and stay, lean.

This idea isn’t new.

In the powerlifting and strength training arena they call it carb back-loading, originally coined by John Kiefer.

In essence, the protocol relies on taking in very low quantities of carbohydrate in the morning, then higher amounts of carbohydrate after resistance training, towards the end of the day.

Again, it’s good to question the theory, and interestingly, I found a recent study relating to this idea of carb timing.

In the study, participants were put on a calorie restricted diet for six months;

  • Either a control group (carbs throughout the day).
  • Or, the experimental group, who ate their carbs mostly at dinner (approx 80% at night).
  • The groups ate the same amount of calories, protein, carbohydrates, and fat (1,300–1,500 kcal, 20% protein, 45–50% carbohydrates, 30–35% fat).
  • The only difference was how they distributed their carbohydrate intake.
  • They all had BMIs greater than 30 to begin with.

What did the researchers find?

Well, the group eating their carbs at night, lost more weight (11.6 vs 9.06 kg) and body fat, compared to the control group.

On top of that, they also experienced better satiety levels, which I think it highly significant;

Greater weight loss, abdominal circumference, and body fat mass reductions were observed in the experimental diet in comparison to controls. Hunger scores were lower and greater improvements in fasting glucose… A simple dietary manipulation of carbohydrate distribution appears to have additional benefits when compared to a conventional weight loss diet in individuals suffering from obesity. It might also be beneficial for individuals suffering from insulin resistance and the metabolic syndrome.

It all sounds pretty promising.

So, why is it that eating most of your carbs in the evening could be beneficial to body composition, and satiety levels?

First of all we need to understand a little about cortisol, since it plays a key part in all of this.

Cortisol

Cortisol has received a lot of flak in recent years, but it is actually a vitally important hormone.

It naturally peaks when you wake up, this is known as the cortisol awakening response (CAR). Also, exercise and acute stress significantly raise cortisol levels.

How Cortisol Works

Cortisol (and its partner epinephrine) is best known for its involvement in the “fight or flight” response. Which works as follows;

  1. You are faced with something stressful.
  2. The adrenals secrete cortisol.
  3. Cortisol prepares the body for a fight or flight response, by increasing glucose in the blood to supply an immediate energy source to your muscles.
  4. Cortisol inhibits insulin production, to prevent glucose from being stored, since you want to use it immediately.
  5. You address or resolve the situation.
  6. Your hormone levels begin to return to normal.

Obviously, this works perfectly well under normal circumstances.

The problem is that many of us are overly stressed these days, meaning our bodies are in a constant state of elevated cortisol levels, and this is where it gets problematic in terms of ill health.

Why Elevated Cortisol Is Bad News

There are lots of reasons why raised cortisol is not good news for your health, but I want to stay focused by discussing those relating to weight gain in this article.

1. Blood Sugars and Diabetes

When you are under stress, cortisol provides the body with glucose (by using gluconeogenesis in the liver) to tap into your protein stores.

As we’ve already seen, this energy is there to help in a fight or flight situation.

The problem is when you have elevated cortisol levels your blood sugars remain high, because cortisol inhibits insulin’s effect, making your insulin resistant. This is bad, because the high sugars in your blood aren’t being dealt with, yet the body continues to pump out insulin, which you are now resistant to.

It could be represented very simplistically like this;

Eventually the pancreas will struggle to meet this high demand for insulin, glucose levels in the blood will remain high, and so this unhealthy cycle continues.

Theoretically speaking, this can increase your chance of becoming type 2 diabetic.

2. Weight Gain and Obesity

If your cortisol levels are repeatedly elevated, studies show this can lead to weight gain;

Central fat distribution is related to greater psychological vulnerability to stress and cortisol reactivity… stress-induced cortisol secretion may contribute to central fat and demonstrate a link between psychological stress and risk for disease.

How? Well, cortisol can take triglycerides from storage and relocate them to visceral fat cells (deep in the abdomen).

This is bad, because visceral fat cells have more cortisol receptors than subcutaneous fat, so greater amounts of cortisol is produced as a result. This further adds insult to injury.

A second way in which cortisol may be involved in weight gain, is related to insulin.

If you have high blood glucose levels and insulin suppression (due to high cortisol), your cells are being starved of the glucose they need. So, hunger signals are sent to the brain, causing you to eat more, perpetuating the situation.

Of course, unused glucose, which can’t make it’s way into the cells, is eventually stored as body fat.

On top of all of this, cortisol is thought to have an effect on appetite and cravings for high-calorie foods, particularly in women;

These results suggest that psychophysiological response to stress may influence subsequent eating behavior. Over time, these alterations could impact both weight and health.

How Cortisol Can Help Burn Fat

So, bringing this fullcircle, what has the all got to do with our study on “carb back-loading.”

Well, as I’ve mentioned, cortisol gradually builds up overnight, peaking in the morning when you wake up.

This is a natural process, and quite normal.

In fact, it is something you can use to your own advantage.

This is because when cortisol levels are high — without elevated insulin levels or chronic stress — like first thing in the morning, it triggers the breakdown of triglycerides into free fatty acids (FFAs) for metabolization (lipolysis).

That means in the morning, cortisol could actually help you burn fat.

But, your diet must be right, for this to happen.

Don’t Eat Carbs At Breakfast

It appears that eating a high carb breakfast is the worst thing you could do for fat loss, providing all of the necessary ingredients to switch your body from being a natural fat burner, to a sugar burning, fat accumulator.

However, by avoiding the typical breakfast, high in carbs, such as cereal or toast, you can boost your fat burning potential. In essence what this does, is allow cortisol levels to naturally reduce (about 2 hours after waking).

On the other hand, if you eat those morning carbs, you keep your cortisol levels elevated, which is not good for the body.

According to Kiefer, a much better time to eat high carb foods is after a good weight training session. And, this is the premise behind the carb back-loading plan.

Diet and Exercise Plan

In addition to the above, to prevent your cortisol levels getting out of control, and constantly being elevated, there are a number of steps you can take;

  • Follow a low glycemic load diet.
  • Eliminate trans fats and other unhealthy omega 6 fat sources.
  • Eliminate or reduce your caffeine intake (2-3 cups of coffee per day can elevate cortisol levels).
  • Drink alcohol in moderation, if at all.
  • Eat lots of whole plant foods, such as vegetables, fruits, legumes, nuts, and seeds.
  • Get enough omega 3 fats into your diet from oily fish or fish oil supplements.
  • Take regular exercise, but do not overtrain.
  • Add probiotics to aid gut health.

Also remember that stress reduction, and getting adequate sleep, are extremely important for keeping cortisol levels at bay.

I’d love to hear your thoughts on this idea of eating carbs at night. Please share your thought in the comments below…

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About Melanie
Melanie is a Registered Dietitian who started Dietriffic in March 2007. Her aim is to make good health attainable and sustainable, without guilt and torture, making her approach popular with those who desire a level-headed approach to good health. Have you got your copy of her free book yet?


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{ 15 comments… read them below or add one }

Mathew December 4, 2012 at 9:00 pm

The study you cite as evidence that eating some carbs at dinner / evening may help with weightloss does NOT suggest that at all.

The study compared two diets, where the only difference was the time of day the carbs were eaten. So the conclusion from that study, is that if you are going to eat significant carbs and protein (the protein is important) then you must restrict calories and you should eat the carbs late.

A much better study would have a range of diets, including a high fat, low carb approach. Then you would find that low carb would trump the other approaches, even without calorie restriction.

The erroneous conclusion being drawn here simply gives people the idea they should be eating carbs, and you will find those people always struggling with weight control because of it.

Reply

Melanie December 4, 2012 at 9:36 pm

Hi Mathew,
I have used this study as a springboard for the rest of my discussion. If you read to the bottom, you will see I certainly do not recommend a high carb diet at all. If you’re interested, see here for more on my take on carbs.

The study showed that eating carbs at night led to more weight loss, than spreading the same amount of carbs out over the day.

In terms of a “better study,” I disagree. You want to put subjects on a diet with as much consistency as possible. So, controlling what they ate, with variations only where you want them, e.g. the timing of the carbs, in this case.

I totally agree with you that a lower carb diet is better for weight loss, than the ratios researchers have used in this study. I am not recommending a high carb diet by using this study as an example. What I want to focus on is the timing of carb intake. This is possible to do because the researchers controlled for all other factors in this study.

Having said that, while I don’t encourage a high carb diet in general, neither do I support a zero carb diet. The point, then, in my article is that when eating carbs, there is evidence that consuming them in the evening may limit the negative impact they can have on weight loss. I go on to demonstrate that with a very lengthy explanation of cortisol and it’s effects.

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Kayleigh Maijala (@confusedtruffle) December 5, 2012 at 4:39 am

This may be unrelated, but let’s say someone works out in the morning to take advantage of the fat-burning zone. (That overnight, your glycogen stores are depleted or close to it and you work out to source your fuel from fats or proteins)

Would eating carbs at night then be fueling the workouts in the morning? Would you just be burning off the sugars from those carbs? Or would you still be burning fat/muscle?
I wonder how it affects that..

Reply

Liisi from FitSmarty December 12, 2012 at 2:07 pm

Well according to some theories (some of them pointed out here by Melanie too) eating carbs at night might have a negative effect on your fat burning zone in the morning.
By eating carbs late at night you get your cortisol level higher than it would normally be in the morning. This will make your body use sugars more than fat during the morning work out session.
The effect however is definitely weaker than it would be with a routine where you eat your carbs right before your work out.

Reply

Melanie December 14, 2012 at 5:02 pm

Hi Kayleigh,
If we take the study I mentioned as an example, the researchers said those who ate their carbs did so mostly at dinner. I suppose I was taking that to mean earlier in the evening, not a feast of carbs right before bedtime, therefore, those carbs would have been burned off or stored up prior to that morning workout.

What Kiefer recommends is probably close to the mark when he says, a much better time to eat higher carb foods is after a good weight training session.

Reply

Liisi from FitSmarty December 12, 2012 at 2:09 pm

I really like the article.
Though I don’t quite agree with everything (I strongly believe that you should eat carbs in the morning!) I like the thought provoking style of the article.. :)

Reply

Melanie December 14, 2012 at 3:37 pm

Hi Lilsi, Thanks for your comments. Do you believe in eating carbs in the morning, then not at night?

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Liisi from FitSmarty December 14, 2012 at 4:40 pm

Yes. I would not recommend a low-carb diet for anybody (who is not professional bodybuilder). But I think you should eat your carbs in the first half of the day. After lunch you may eat carbs as well, but those should really be limited.
This is quite “traditional” way of looking things, but it has proved itself in my practice.
However, I feel intrigued with your idea of eating them late at night. I would not recommend it to a beginner or someone who is trying to lose weight.
But an experienced “healthy lifestyler” surely can try it out and see if it does him/her any good or not. Would be an interesting experiment..

Reply

Melanie December 14, 2012 at 5:06 pm

Absolutely, it would make a very interesting experiment!! I find it really interesting, too.

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Rayca September 5, 2013 at 9:30 pm

@Liisi –Why do you keep saying “late at night?” No one has suggested or implied that and the article didn’t mention it either. Dinner or after evening workout (which would be dinner for that person). Try dealing with insomnia and eating your carbs only in the AM. That’s my dilemma. Those carbs are long gone by the end of the day and believe me, I’ve been dealing with it for many, many years and nothing (not even sleeping pills work). Please, no references to melatonin, magnesium, gaba, etc., etc. Guess what does work. Carbs at dinner. I don’t eat them any other time now. Doesn’t matter whether I work out or not. It stops insomnia cold. Now could that still be adrenals? Sure. But it’s a needle in a haystack. Ins. cos. don’t even know what adrenals are. Not sure if there are even credible tests for adrenals. I know much about tests and hormones. Carbs are cheap and if you find your sweet spot, they work. Most low carbers that have sleep issues (low carb causes sleep issues for tons of them. Period.) use the night time carb strategy (whether they’re willing to admit it or not).

Reply

jennifer December 29, 2012 at 9:24 am

Hi, great article and thanks for holding the space for discussion.
Here’s another angle, to do with evening carbs and sleep, and how that factors in to weightloss and other aspects of wellness.

I tend to follow a low carb regime, paying attention to my body’s messages in the last couple of days I have added more carbs than i would usually feel comfortable with ( a regular portion) to my evening meal and notice that this has really improved my sleep.

I suffer from terminal insomnia – early waking – now I might wake at those early times – typically around or before 5am – now i can get a second bout of sleep, which also is my rem/dreaming sleep. I consider the dream phase to be crucial to emotional and spiritual health so am super pleased to be experiencing this again.

I wonder whether evening carb consumption relates to morning cortisol levels and so facilitates a thorough nights sleep.

I am a self-indoctrinated carb-fearer and on one hand am mindful that it might slow weight loss. But I feel courageous enough to aim for the pay off of a thorough nights sleep on a regular basis with all the additional wellness benefits – feeling more rested = less irritable, better digestion and skin, less anxiety, all of which factor in to sustainable weight loss, I feel.

As suggested in your article am going to pursue this as an experiment over the next week or so, including carbs in the evening meal, mindfully ie if it sets off increased cravings than I will curtail and will be eating good /unprocessed carbs eg sweet potato, red and wild rice.

Blessings of health to all!

Reply

Melanie February 7, 2013 at 10:29 pm

Hi Jennifer, that is really interesting. Sorry I’m only getting to respond to you now. How did your experiment go in the last few weeks?

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Rayca September 5, 2013 at 9:38 pm

The same for me, Jennifer. Isn’t it great to get a good night’s sleep? I’m still working on just how many carbs (oats for me) to have but I’m getting it dialed in. I also do very well with fat/carb mix. I’ll have coconut milk (just a small amt.) in with about 1/2c. oats. I still wake up but I fall right back asleep. I even sleep in sometimes. I will admit that I’m a little bloated in the AM (not like when I ate carbs full time). But I don’t eat until I’m hungry now and I’m still trying different carb amounts. I may try having dinner earlier, taking a hot bath and then retiring. That’s my next step.

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George March 29, 2013 at 7:09 am

Hi Melanie,

I just want ask you about this way of thinking ? The experimental group (80% C at night) ate 1300-1500 kcal per day.. For me basal metabolic rate is 1868 kcal. I am very active, so for example I should ate about 2000 kcal and 40% are carbs (4 kcal per g of carbs is about 800 kcal which is 200 g of carbs). If I have to eat 80% of this amount at dinner. It will be 160g. It is too much, isn’t it ? How should I plan the carbohydrates during the day and at dinner. Do I really have to eat 40g per breakfast, snack, dinner and the rest at night ??

Thank you for your opinion.

Kind regards

George J.

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