Uh oh.
Can I guess what you've done?
You've clicked on this thinking: "Aw no, I eat lots of fats after my workout - have I been robbing myself of gains?
Don't worry, you're one of many.
I particularly am guilty of loving the big fatty burgers and fries sometimes after my training, so this super fresh study has certainly piqued my interest (1).
Now I will point out it was done into endurance athletes so this doesn't necessarily mean it will translate into those of us looking to gain muscle mass in the gym. But on the flip side this doesn't mean it WON'T, either.
I'm reporting on this research to make you aware so you can then make your own decision!
In the study, 10 males exercised twice per day with 3.5 hours in between sessions.
Session One: Running 8 x 5 min at 85% VO2peak (HITT)
Session Two: Running 60 minutes at 70% VO2peak (LISS).
In a repeated measures design, runners exercised under different isoenergetic dietary conditions consisting of:
High Carb: 10g carbs, 2.5 protein and 0.8 fat per kilogram of body weight (for an 80 kilogram person: Protein: 200 Fat: 64 Carbs: 800)
or reduced carbohydrate but with high fat availability in the post-exercise recovery periods: 2.5 carbs, 2.5 protein and 3.5 fat per kilogram of body weight (for an 80 kilogram person: Protein: 200 Fat: 280 Carbs: 200)
Now as you can see, that's a lot of fat!
So what did they find?
The muscle growth pathway P70S6K was higher 3 hours after the LISS session in the high carbohydrate group vs the high fat group (72.7 ± 51.9 vs 44.7 ± 27 fmol.min mg).
The researchers conclude:
"Post-exercise p70S6K1 activity is reduced under conditions of high fat feeding thus potentially impairing skeletal muscle remodelling processes."
The simple conclusion here is that a high fat intake following aerobic endurance training suppresses the intracellular signaling response (P70S6K) associated with muscle protein synthesis - but the jury is out on whether it will do the same after a resistance training workout.
Remember: this is in comparison to a low fat intake - with BOTH protein intakes being the same (great study design!).
Although muscle protein synthesis wasn't measured directly, it tells us that maybe just maybe, a high fat intake after training could rob us of gains.
The Old Bro Science Logic - No Fat After Training
Whilst some may read this article and say: "I've known this for years!" - chances are they haven't known specifically this finding - because it's all relatively new.
I've written just very recently about how higher fat diets may be worse for muscle growth - but again we've still a lot more to learn here before we start shouting any definitive statements in regards to post-workout fats from the roof tops.
But the old broscience school of thought was that: "No fats after training bro - they'll slow down the absorption of carbs and protein and rob you of your gains!"
Now first things first - YES they will slow down the absorption of your protein and carbs - but slowing down the digestion of both of these macronutrients is of no concern for muscle growth. What matters is that you consume your macronutrients over a given day.
Slowing down the digestion of protein and carbs stems from the false ideology that the anabolic window is important for muscle growth - which is not true. The fact is that nutrients DO NOT need to be consumed and absorped as fast as possible within 30 minutes for optimal muscle gains.
The other incorrect notion is that a high insulin spike via carbohydrates is needed post-workout for maximising gains. By having too much fat post-workout some people still think it will blunt the anabolic insulin response, slow down the carbohydrate absorption, and we'll be robbed of gains.
But this theory has been disproven multiple times (2-5).
There's simply no requirement for a high GI spike of carbs rapidly post-workout for maximum muscle growth.
The other issue is glycogen resynthesis.
Us poor resistance trainers - we've been sold just about everything stemming from endurance training findings as fact from broscientists and supplement companies.
Again, as I've said, I'm not saying this post-workout fat intake for muscle signalling is a load of rubbish, but ironically it HAS stemmed from an endurance athlete study!
But hey, there's a first time for everything!
But back to glycogen resynthesis - the other lie us resistance trainers have been told. This incorrect school of thought has always been: "no fat after training bro, you need to replenish glycogen quickly for your next workout..."
In this research, there was no difference between a post-workout drink of 66% carbs, 23% protein and 11% fat - compared to a 100% carb drink (6). Both carb types were the same, too.
Basically, fat won't slow down your ability to replenish glycogen. If you're a resistance trainer training at the same time daily, glycogen replenishment is not a concern. But if you're an endurance athlete who is competing again less than 24 hours later, then yes, glycogen replenishment is important to you. Context is everything.
Moreover, the BIG nail in the coffin saw a control diet of 7g/kg of high-GI carbs with two different experimental treatments given to subjects who trained for 2 hours at 75% of their VO2max before finishing with 4 x 30 second sprints (7).
The other treatments consisted of the carb intake outlined above (control) with the added fat (1.6g/kg) and protein (1.2g/kg) with the same calorie deficit consisting of the carb intake and the added carbs to equal the calories of the experimental treatments.
So what did they find?
Even considering the high fat intake seen in one group - there were NO differences in muscle glycogen content 24 hours following the training when compared to the low fat group.
So you can put that one to bed, too.
Practical Nutrition Applications
So whilst some people may claim to have known that fat is "bad" post-workout for years, it's most likely for the wrong reasons.
Remember - there's still no solid conclusion yet that it interferes with muscle signalling and thus growth after resistance training.
However for what it's worth, I would say that we should look at reducing our fat intakes post-workout, and having them maybe for lunch or before bed - if we wanted to be precautionary.
If you don't - no stress - just keep eating what you will until some more concrete and direct evidence somes to light!
"Stay Fit, Stay Flexed!"
References
(1) Hammond KM et al. Postexercise High-Fat Feeding Supresses p70S6K1 Activity in Human Skeletal Muscle. Med Sci Sports Exerc. 2016 Jun 20. [Epub ahead of print]
(2) Staples AW, Burd NA, West DW, Currie KD, Atherton PJ, Moore DR, Rennie MJ, Macdonald MJ, Baker SK, Phillips SM. Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Medi Sci Spots Exerc. 2011 Jul;43(7):1154-61. doi: 10.1249/MSS.0b013e31820751cb.
(3) Koopman R, Beelen M, Stellingwerff T, Pennings B, Saris WH, Kies AK, Kuipers H, Van Loon LJ:Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis. Am J Physiol Endocrinol Metab 2007, 293(3):E833-842.
(4) Glynn EL, Fry CS, Timmerman KL, Drummond MJ, Volpi E, Rasmussen BB: Addition of carbohydrate or alanine to an essential amino acid mixture does not enhance human skeletal muscle protein anabolism. J Nutr 2013, 143(3):307-314.
(5) Gorissen SH, Burd NA, Hamer HM, Gijsen AP, Groen BB, van Loon LJ. Carbohydrate coingestion delays dietary protein digestion and absorption but does not modulate postprandial muscle protein accretion.J Clin Endocrinol Metab. 2014 Jun;99(6):2250-8. doi: 10.1210/jc.2013-3970. Epub 2014 Mar 14.
(6) Hansen KC, et al. Exercise increases the proportion of fat utilization during short-term consumption of a high-fat diet. Am J Clin Nutr. 2007 Jan;85(1):109-16.
(7) Burke LM, et al. Effect of coingestion of fat and protein with carbohydrate feedings on muscle glycogen storage. J Appl Physiol. 1995 Jun;78(6):2187-92.
Author
Dayne Hudson