Could Those Nighttime Carbs Actually Benefit You?
Who DOESN’T love carbs at night?
You sit down on the couch to watch a movie, and you want popcorn, ice cream, or a bag of chips, right? A piece of salmon and some asparagus isn’t going to cut it.
Carbs are tasty enough as it is, but when the late night munchies come into play, they get even tastier.
Fortunately, most of us know by now that it’s okay to eat carbs at night, and consuming them before you go to bed is no more likely to lead to fat gain (or blunt fat loss) than consuming them at any other time of the day.
But a few years back, when a diet hit the mainstream that actively encouraged you to eat almost all of your carbs at night, people in the training and nutrition industries lost their minds.
Some people cried witchcraft, while others proclaimed that this was a gift from the dieting gods.
The diet in question: Carb back-loading.
So what’s the science behind the methods? Is it bothering with, or just another fad to add to the ever-growing pile of flash-in-the-pan diets?
What Is Carb Back-Loading?
While there have been people back-loading for decades, the concept made the big time when John Kiefer published his “Carb Back-Loading” book in 2012.
The premise is simple: You eat little to no carbohydrate throughout the morning and afternoon, right up to around 5pm, when you break your carb fast and continue eating them right up until you go to bed.
To follow the plan optimally, Kiefer suggests training sometime around mid-afternoon, so that your first carb-heavy meal comes immediately post-workout. Advocates of carb back-loading point to two studies to back up their reasoning for suggesting such an approach.
The first study [1] took 10 women and compared their body composition after 6 weeks. Both groups were on a calorie-restricted diet, with half the women spreading calories throughout the day and the other half eating more at night.
The nighttime group did lose more fat, but the two main issues with this study were the small sample size and the fact that researchers used electrical conductivity devices to assess muscle mass and fat mass ratios. This is far from the most effective way to measure body composition, and so any results have to be taken with a grain of salt.
The second study [2] had a bigger sample size (43 overweight and obese men), and again, the carb back-loaders reported greater satiety and lost more weight. The trouble here though, was that calorie intake was self-reported, which is notoriously inaccurate, especially in overweight and obese individuals [3].
The ‘Science’ Behind Carb Back-loading
The theoretical fat loss advantage obtained through carb back-loading is based on fluctuations in insulin sensitivity.
Insulin is a hormone that is released when a person eats carbs, and to a lesser extent, protein. It allows carbs (in the form of glucose) to be absorbed from the bloodstream into the liver, muscle, and fat cells, where they are stored as fat or turned into glycogen and later used as energy.
“The theoretical fat loss advantage obtained through carb back-loading is based on fluctuations in insulin sensitivity.”
There’s some evidence to suggest that our cells are less sensitive to the hormone insulin later at night than in the morning. Alternatively, muscle cells are more sensitive to insulin directly after exercise. This increased sensitivity to insulin after exercise allows the muscle to quickly replete stored carbs that were used during training (called glycogen).
So why does all of this matter?
By depriving your body of carbs in the morning when they’re more likely to be stored as fat, and consuming them after an evening workout or late at night when they’re less likely to be stored as fat, proponents of carb back-loading believe that the body’s energy balance mechanisms can be overridden.
Here’s the kicker though — insulin isn’t the almighty regulator of fat loss that it’s been made out to be.
While insulin does help regulate fat loss and gain, it doesn’t hold the master key. If it did, taking BCAA’s by themselves would make us fat (since this also increases insulin), and eating a hypocaloric higher carb diet would also lead to weight gain. But this doesn’t happen.
Fat loss comes down to how much you eat, not when you eat it.
You can’t outsmart your body by eating carbs at certain times of the day, and you can’t override energy balance! Calories in versus calories out will always be more important than insulin levels.
“Fat loss comes down to how much you eat, not when you eat it.”
An Open and Shut Case? Not so Fast…
Although there’s no reliable data to support the notion that you will get any benefit in body composition by saving all of your carbs for later in the day, that’s not to say you should avoid back-loading like the plague either.
Aside from being in a calorie deficit and getting sufficient protein, enjoyment is perhaps the biggest factor in getting results with your diet [4]. Therefore, if you love saving your carbs until late in the day, then provided you’re hitting your macros, this way of eating could lead to better results as you’re more likely to stick with it.
Many dieters find that as macros get lower, willpower is tested the most in the evenings. Having some carb-rich comfort food to turn to at the end of the day can really help you stay on track.
Carb back-loading may also have an advantage over intermittent fasting when it comes to maximizing muscle growth, purely because you’re eating protein throughout the morning and afternoon. Even though carbs may be minimal during this window of time, you’re still spiking your muscle protein synthesis levels throughout the entire day.
Carb back-loading may also have an advantage over intermittent fasting when it comes to maximizing muscle growth, purely because you’re eating protein throughout the morning and afternoon. Even though carbs may be minimal during this window of time, you’re still spiking your muscle protein synthesis levels throughout the entire day.
A Few More Things You Need to Know…
Before you give carb back-loading a whirl, there are a few things you need to know.
Like any diet that promotes extremes, it’s easy to get carried away with back-loading and to develop a disordered relationship with food.
Additionally, the official carb back-loading book advises that to get the most out of the protocol, you should eat mostly high-GI carbs in the evening. This can make getting enough fiber difficult, and can also potentially lead to bloating and discomfort — not mention going to bed feeling stuffed!
Finally, the importance of pre-workout nutrition can’t be underestimated either. Very few people out there are able to perform optimally with little to no carbohydrate in their system before a training session. You might be able to do it, but going carb-free all day and pushing through your workouts on nothing but fat and protein may impair your performance and compromise recovery [5, 6].
Is Carb Back-Loading Right for You?
If you genuinely feel that you function okay on minimal carbs during the day, can get a productive workout like this, and you enjoy this way of eating, then, by all means, go right ahead.
At the risk of sounding like a broken record, total daily calories and macros matter far more than nutrient timing, so provided you’re hitting those, you could consider a back-loading approach.
Just be aware that it probably isn’t optimal from a physiological and performance perspective. You may also want to tweak the traditional protocol so you eat more nutrient-dense forms of carbs, particularly if your macros are low and you want to feel full and ensure you’re getting all your micros and fiber to keep you healthy.
References:
[1] Keim N, Van Loan M, Horn W, Barbieri T, Mayclin P. Weight loss is greater with consumption of large morning meals and fat-free mass is preserved with large evening meals in women on a controlled weight reduction regimen. The Journal of Nutrition. 1997;127(1):75–82.
[2] Pateyjohns IR, Brinkworth GD, Buckley JD, Noakes M, Clifton PM. Comparison of Three Bioelectrical Impedance methods with DXA in overweight and obese Men*. Obesity. 2006;14(11):2064–2070. doi:10.1038/oby.2006.241.
[3] Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine. 1992;327(27):1893–1898. doi:10.1056/nejm199212313272701.
[4] Johnston BC, Kanters S, Bandayrel K, et al. Comparison of weight loss among named diet programs in overweight and obese adults. JAMA. 2014;312(9):923. doi:10.1001/jama.2014.10397
[5] Tarnopolsky M, Gibala M, Jeukendrup A, Phillips S. Nutritional needs of elite endurance athletes. Part I: Carbohydrate and fluid requirements. European Journal of Sport Science. 2005;5(1):3–14. doi:10.1080/17461390500076741.
[6] Miller SL, Wolfe RR. Physical exercise as a modulator of adaptation to low and high carbohydrate and low and high fat intakes. European Journal of Clinical Nutrition. 1999;53(s1):s112–s119. doi:10.1038/sj.ejcn.1600751.
