Fact Or Fiction? Carb Timing Is Crucial For Muscle Gain And Fat Loss

3094702193_d91547b7efIf you recall last week we looked at eating carbs at night and I showed how it doesn’t matter when you eat carbs, just that you hit your calorie and macronutrient needs throughout the day. One topic I mentioned I was questioning was if insulin sensitivity really is impaired at night or if that may yet be another myth in the bodybuilding world. Today I will be taking a closer look at that very subject, as well as how insulin sensitivity is effected depending on different stimulus.

First, why is insulin sensitivity important to us? Well it’s important because the more glucose you can dispose using less insulin will be better as it will reduce fat accumulation not to mention keep you healthier. If you eat too many fast carbs you raise your blood sugar. Your body releases insulin to bring blood sugar down. Unfortunately you can only bring down so much blood sugar at one time so if you consume too much of it, your body will store it as fat. Perhaps better put would be your liver and muscles can only store so much glycogen, so excess will be stored as fat. This is why those of us who do a lot of resistance training not only can eat more carbs, but should. Your muscles need those glycogen stores to be effective. But if you are inactive and you eat a lot of carbs, especially low fiber high sugar carbs, they will be stored as fat.

You see you have limited storage for carbohydrates in your body, but you have unlimited storage for fat. If you have a healthy metabolism it only takes a little bit of insulin to bring your blood sugar down. Long story short, good insulin sensitivity helps keeps you healthy and fit. Being more insulin sensitive is a good thing, there are many who believe it to be the opposite because of the way it sounds. Don’t let it fool you, the more insulin sensitive you are the better off you will be.

There is research available to show that insulin sensitivity is worse at night compared to the morning. (1) What this fails to address, however, is the fact that your morning meal comes after fasting overnight while you sleep. zuzkalight-zcut-reviews-gympaws-fit-girls-crossfit-gloves-339x480To be more fair it would be better to look at eating a meal such as lunch compared to eating a meal at night. This is something Biston et al. (1996) (2) looked at. They took nine young subjects and spaced out their meals between 8:30 AM, 2:00 PM and 8:00 PM giving them the same amount of carbohydrates at each meal. They found that insulin sensitivity and glucose tolerance were different between the morning meal and the other two meals but there was no difference between the 2:00 PM meal and the evening meal. I think it would be fair to say it’s not the time of day the influences insulin sensitivity, but how long you’ve gone without stimulating an insulin release.

This would also fall in line with the research by Sofer et al. (3) we looked at last week where the police officers who ate the majority of their carbs at night had baseline insulin levels significantly lower than those eating carbs during the day. It was the long layoff from carbs that improved insulin sensitivity, not the time of day.

While it does appear that insulin sensitivity is decreased with age (4) there is also research that shows it may have more to do with lifestyle habits than it does aging itself. (5) Insulin sensitivity is increased when you lower body fat percentage (6) and the ability to reverse insulin resistance with exercise appears to be the same regardless of age. (4) Certainly good news for anyone getting up there in age who wants to improve their health and body composition.

strong-hanging-leg-raise-for-absExercise has been shown to increase insulin sensitivity during and for a while after exercise. (7) This is partially why you’ve probably heard it’s important to get some fast carbs in your system post-workout. People believe because insulin is a potent storage hormone it will help shuttle the amino acids you consume post-workout into your muscles and help increase muscle-protein synthesis thus making insulin a very anabolic hormone. However, as I’ve shown you before insulin actually isn’t anabolic at all under normal physiological conditions on it’s own (at least in adults, it’s possible insulin can be anabolic in youth) and even in combination with protein post-workout the research shows if anything just a very small increase in protein synthesis but not a statistically significant difference. (8)

Just because insulin isn’t anabolic, however, doesn’t mean there isn’t some merit behind eating carbs post-workout. Since working out increases insulin sensitivity you are more carb tolerant post-workout. So eating a large portion of your carbs post-workout could make some sense. You just don’t need to spike insulin with 100+ grams of simple carbs as you’ve probably often heard in popular bodybuilding magazines. The only reason you would need to replenish glycogen stores that fast is maybe if you have another workout coming later that day.

So what have we learned here today? While insulin sensitivity does tend to decrease at night it’s not because of the time of day but because of how often and how recently we have spiked insulin levels throughout the day. Zgym-image_BeginnerExercise does increase insulin sensitivity temporarily but also long-term if it leads to a decrease in body fat. How can we use this information to our benefit? Well it would seem like the ideal times to eat a large portion of your carbohydrates would be when you are most insulin sensitive, which would be first thing in the morning after an overnight fast and post-workout.

Wait, doesn’t this conflict with what I told you last week? You bet it does, because while it would seem like there are more ideal times to consume certain nutrients, the bottom line is hitting your calorie and macronutrient needs however works best for you will be enough. If these ideas work well with your lifestyle it could be a good idea to work under those circumstances. If they don’t, then don’t worry about it. The rest is splitting hairs and doesn’t appear to make a significant difference. It’s kind of like meal frequency. There may be more optimal timing, but at the end of the day I don’t believe it makes a significant difference at all.

Fact Or Fiction? Carbs At Night Make You Fat

This article was written and researched by Colin DeWaay

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10 comments for “Fact Or Fiction? Carb Timing Is Crucial For Muscle Gain And Fat Loss

  1. Brian Klein
    April 1, 2014 at 3:21 pm

    Interesting thoughts on this Colin. I’ve always wondered why the timing was so important. I know some people have severe energy drains after a workout, likely due to decreased glycogen, and that would be a good reason to eat good carbs post workout. So as always, it depends on you how you feel.

    Have you looked into carb backloading by any chance. I’ve seen it in some nutrition circles, usually in reference to body building and exercise. (I don’t know as much about nutrition as it effects bodybuilding, as I do about nutrition in reference to general health.)

    • April 1, 2014 at 4:19 pm

      Hey Brian,

      I don’t think timing is that important, but it can have some advantages. I’ve actually done carb-backloading in the past and written about it. I had pretty good success with it for fat loss, not sure I’d do it again or not. My opinion on the matter has kind of swayed to the more carbs you can eat while still losing fat the better not only for long-term success but for retained strength. But I cannot deny it was effective for me. I wouldn’t recommend for everyone though.

  2. March 31, 2014 at 5:47 pm

    Great article, Colin, but it’s important to note that it just scratches the surface of an issue so complex that even the scientists studying it can’t agree. This topic is of utmost importance to me as I’m battling type 2 diabetes and approaching 60 years of age, so I’ve looked into it a lot. Being small-framed it took me about 30 years of on-again, off-again lifting to get my weight up to 175 pounds – then the diabetes hit and my weight dropped to 138 pounds within 3 months. Worst of all, it was almost entirely muscle loss – my waist line barely changed.

    When I started looking into it, I found that the liver converts glucose to glycogen for use by the muscles, but only insulin can transport the glycogen to the muscles, and how much of the glycogen actually gets into the cells is entirely dependent on the condition of your insulin receptors. Since the sensitivity of the receptors declines from increased insulin over time, less and less of the glycogen is taken in by the muscles and a greater percentage ends up being taken in by your fat cells.

    This validates your point that it’s the length of time since your last carb intake that determines the rate of absorption to a great extent, but it also shows how misleading a study like the one with the police officers can be – while their massive carb intake in one meal helped in the short term, that big an insulin hit each day would probably lead to dulled insulin receptors and type 2 diabetes over a few years.

    All of that notwithstanding, I feel the person’s genetics play more of a role than nutrient timing or the volume of their workout, especially for strength athletes. Andy Bolton, the first man to deadlift over 1,000 pounds, points out that while the world record for deadlifts is around 1,200 pounds now, the record for someone weighing 160 pounds is around 700 pounds. For building muscle, the biggest issue seems to be ego – we know that time under tension and full range-of-motion are the keys, but most people end up trying to go heavier and heavier, ignoring those two factors.

    To get an idea of how complicated the issue of insulin and carbohydrate uptake is, here’s a good research synopsis on that issue: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1204764/

    Thanks for the great article – you and Matt always provide great info that actually makes people think!

    • March 31, 2014 at 6:50 pm

      Thanks Doug for the great feedback and sharing your story. I think what you touched on with genetics plays a key role for everything, including how well each body will handle larger insulin spikes over time. There of course will always be anomalies as well, which is why it’s so important to know your body.

      It sounds like what you suggest, which is what I currently do, is a fairly even spread of carbs at each meal throughout the day? After all like I mentioned I believe the most important factor is hitting your numbers, regardless of anything else.

      As for the strength and time under tension, that’s why I like to incorporate a strategy that includes lifting for strength and a larger focus on time under tension on separate days but doing both each week. The stronger you are for those hypertrophy workouts, the more muscle you can expect to have.

      I’ll have a look at that research, thanks Doug! I’ll be interested to see what you have to say about what I’m writing about the next upcoming couple of articles, as it all ties together in a sense.

  3. Matt Taylor
    March 31, 2014 at 8:57 am

    It’s my understanding that post workout your body is too busy trying to remove damaged muscle by products from the trained muscles to have any immediate use for carbs at all. It makes more sense to me to ingest them before you train in order to get a good workout in. Pre workout nutrition is your best post workout nutrition. This just further illustrates how irrelevant trying to time nutrition to your bodies momentary needs is. On one hand it makes sense to do A until you realize doing B would be better or C would be even more ideal and on and on. Just eat a good diet and train hard.

    • March 31, 2014 at 11:44 am

      Just eat a good diet and train hard, you got that right. That’s exactly what I’ve been preaching through my hormone series “anabolic window” series and everything else. Bottom line is if you eat what you need to eat and train hard, that’s what will get your results. Do whatever you need to do to get a good workout in, regardless if that is “ideal” for hormones or anything else.

      • Matt Taylor
        March 31, 2014 at 11:49 am

        I think that almost all muscle gain related problems are due to not training hard enough and diet is the only problem when it comes to stalled fat loss. Trying to make a science out of it is just taking away from the real issue.

        • March 31, 2014 at 12:28 pm

          I think diet is a problem for many people who are hard gainers with muscle gains as in they aren’t eating enough, but not things like when to eat. Often times it does seem, however, that people are so worried about doing the “perfect” things that they end up spending more time learning than they do actually executing. Give your body a reason to grow and it will.

        • Brian Klein
          April 1, 2014 at 3:13 pm

          Diet is likely an issue with fat loss, especially if someone is eating too many carbs, or way too many calories. Too high of protein intake can cause insulin spikes that lead to fat storage as well. But there are a number of other factors, such as stress, cortisol levels, and sleep, among others that can keep the body from letting go of fat. In some cases, overtraining (a form of stress) could stall fat loss. There’s also been some interesting research around set points. I don’t have the links off hand, but your body gets used to a certain amount of fat stored. When you start to lose that fat, it thinks there’s a famine happening, so it tries to hold on to it, and slows down metabolic processes. So it’s usually much more complicated than addressing diet, even if diet is usually the best way to address unwanted fat stores.

          • April 1, 2014 at 4:35 pm

            Indeed protein to a lesser extent can and will spike insulin levels. Many of the other factors you mention in a way all work synergistically. Lack of sleep, high stress and high cortisol all contribute to each other. While fat cells generally won’t generate after childhood and only get bigger, I do believe it’s possible to create new fat cells if one gains a very significant amount of fat. This is something I need to look closer at though. If that’s true, it of course would be more difficult to lose fat. This is why as I mentioned above I recommend for most people who have a decent amount of weight to lose to keep calories and carbs as high as possible and go at weight loss slow. Going at it too fast is what causes what you are referring to with the body trying to hold onto fat. If you go slow and start with high carbs, when you do reach a sticking point you have room to play with and drop them again. If you start too low you can’t go any lower without going into “starvation mode” if you weren’t already there. This is why crash dieters have no success. They lose weight super fast, their metabolism slows down to a halt, they no longer can lose anymore weight because of it and quit. Except now they are going back into their old eating habits with an even slower metabolism than before. But I have gotten way ahead of myself here! ha

            Anyway there are many factors that come into play when it comes to fat loss (and muscle gain) but most of those factors, including all the hormones at play, are mostly influenced by exercise, diet, sleep and stress.

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