Optimizing Carbs for Training During Fat Loss

A question I receive a lot when someone is looking to lose some body fat is "how low should my carbs be"?  

It seems more people are willing to drop carbohydrates these days than fat to lean out.  The pendulum always swings from one side to another and the job of an educator or coach is to bring more people back to the middle, where common sense and long-term application live.  People need to spend time away from extremes to actually find out what works for them and develop good habits; from there it's up to them which side of the bell curve they drift towards, if any.

A huge mistake in drastically reducing carbohydrate intake while dropping body fat is multiple-fold.  For one, you lose a lot of your food sources which can make prepping and planning meals more difficult.  For some, they do not find much satiety from fats and if carbs are low, fat should not also be low in most cases. Low carb, OK.  Low fat, OK.  Low carb AND fat, not OK.

Going too low?

The biggest mistake is neglecting to keep adequate carbohydrates in to support your training.  Yes, you can live without carbohydrates but consider that ketosis is an emergency backup system to keep you alive in times of low energy and low carbohydrate availability.  You'll convert excess protein to glucose when possible and it doesn't take much carbohydrate to snap you out of ketosis.  Just because you can live there, doesn't mean you should.  Research has been conducted that shows after keto-adaptation, athletes can perform as well as those consuming high carbohydrates.  However, ditching all carbs to go through a multiple-month adaptation process in which performance DOES decline, to finally get to a place where you simply perform as well (not better) than before seems like a giant waste of time.

Glucose and carbohydrate intake fuel your brain (85-110g per day for women), nervous system and of course provide energy for muscular contractions.  Simply having higher glycogen stores, as referenced here also promotes greater anabolism, decreased recovery time, decreased immunosuppression, decrease muscle protein breakdown and fuel higher intensity during exercise.

If going very low in carbohydrates means decreased performance in the gym, possibly limited muscle growth, less resilient immunity and slower recovery time it doesn't sound like a very good trade off. If you want to lean out you certainly want to be able to train hard.  Training is the stimulus that helps you retain (and even build) muscle during a calorie deficit.  The harder you can train, the larger the stimulus and the  larger the adaptation.  Training like a wimp because carbohydrates are low is a surefire way to spin your wheels and not make progress.

I'd venture to say that going into the gym and being able to crush your workout, add weight or reps, decrease rest time, get a solid pump and have the energy to put effort in from beginning to end is optimal.  If higher resting states of stored glycogen allow you to do that more or improve upon previous performance, what is there to lose?

Fat loss is not a carbohydrate game

In terms of fat loss, your calorie deficit is the largest factor in your progress.  Protein optimizes repair and growth among other things and much of the rest comes down to preference.  I don't recommend a very low fat diet simply because you'll start to see hormonal issues in people, it limits your food choices, makes meals unpalatable and isn't sustainable.  But opting for very few carbohydrates so you can eat loads of fat will not improve gym performance.

Increased carbohydrate stores and ingestion in and around workouts does limit the amount of lipids (fat) you burn during exercise.  Not a concern for most of us lifting weights since fat is a slow-ass fuel source anyway and doesn't fuel high intensity activity.  Training, as we have covered multiple times, is not the main catalyst for fat loss - your calorie deficit is.  Training is the catalyst for improving fitness and adequate carbohydrates allow for better training in most cases, which allows for better fitness.

We need to flip the paradigm most people see carbohydrates in.  Take a look at a sweet potato.  Does it conjur up ideas of insulin, love handles and diabetes?  If so, your ideas are misguided and lets work on shifting that.  That sweet potato is in fact, like any other food source, a source of calories. The way in which it is digested and assimilated is different than proteins or fats but they all contain calories and they all provide energy. Overeat any one food source and those excess calories can be stored as fat. 

However, each food source, or macronutrient if you will, has it's own unique purpose.  Carbohydrates, as explained above do much more than just fill your stomach.  They are the preferred fuel source of your biological system and for many people, the system runs best when they are included in at least moderate amounts. That sweet potato will be digested from a starch into simple sugars, pass through the intestinal lumen into the bloodstream and be stored as glycogen in the muscles or liver, utilized by the nervous system, oxidized as energy to make pyruvate or stored as body fat.  Body fat storage is only an issue if your calories are in excess.  If they aren't, you're probably just fine.  In this case you get to reap the benefits of fueling your muscles, brain, nervous system and all the downstream effects of that.

Downsides to low carb

I have no problem admitting that some studies show that training in a low-glycogen state show better fat adaptation during exercise (duh) and better aerobic endurance adaptation. This isn't that surprising when you take into account that long-duration cardiovascular exercise shifts to a more lipid-fueled state anyway.  Training in a way that potentiates that makes sense.  However, for the accrual or maintenance of muscle mass and training with weights we can't expect that same adaptations.  Also, simply having higher circulating levels of free fatty acids during exercise does not mean you burn them all off.  Women in particular have higher circulating levels of FFAs during exercise but the fatty acids not used for energy simply go back into fat cells.  Availability and usage are two different things.

Low glycogen states also result in an increased catecholamine response during exercise (epinephrine and nor-epinephrine). For freeing up fatty acids and pushing the liver to release glucose, great.  But constantlt pushing this can limit recovery time, increase muscle protein breakdown, dampen immune cells and stress you in unnecessary ways. You absolutely need some cortisol and adrenaline to enhance fuel release during exercise but chronicly elevated levels can cause burnout, fatigure and decrease recovery.

Again, we come back to the argument of, if going low carb or keto is, at best, only JUST AS GOOD, why do it? You have a lot to risk and not much to gain.  Diabetics, those with PCOS and some other special cases certainly need to have more tightly controlled carbohydrate intakes but for everyone else, they are part and parcel of a great diet.  When you consider that most recommendations are for somewhere around 40% of calories to come from carbohydrates, it really isn't that much.  40% of 2000 calories is 800 calories which is 200g of carbs.  You have the ability to store about 100g of glycogen in the liver and 400g or so in your muscles.  A daily intake of 200g is NOT pushing anyone over capacity especially if they are training hard and getting 8,000-10,000 steps per day.  We're not taling about 600g of carbs a day here, people!

But dragging your intake all the way down to 75-100 gets you the worst of both worlds...not quite keto but not enough carbs to do anything intense.  50g or less pushes keto but at the cost we discussed above.

When you have more to lose, such as in a fat loss phase but literally and figuratively speaking, why increase the risk? I'm not here to argue anyone's results or to tell you the way you did or are currently doing things is flat out wrong.  I don't even want to convinve you that the way I think is the best way.  Instead, I'da rather present some evidence that brings you back to the middle so you can make more informed choices and have other options for your training and nutrition. 

For every person who does well eating 200g carbs per day there is someone doing just as well at 75g or 500g of carbs.  Could they do better if than changed things?  Perhaps, but you won't know unless presented with the information that helps you make a well-educated choice.  For those who equate leaning out with eating "no carbs" I present this blog  as an alternative theory.  Partly because I have seen too many people making things harder than they need to be and as many others getting less-than-optimal results because they can't train and recover the way they need to on very low carbs.

Food, I mean CARBS, for thought.

In Part II I'll go over setting up carbs in a fat loss phase top enhance your results both in the gym and out.


Regulation Of Muscle Glycogen Metabolism During Exercise: Implications For Endurance Performance and Training Adaptations

Mark Hearris-Kelly Hammond-J Fell-James Morton - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872716/

More than a store: regulatory roles for glycogen in skeletal muscle adaptation to exercise
Andrew Philp-Mark Hargreaves-Keith Baar - American Journal of Physiology-Endocrinology and Metabolism - 2012