Does Fasting Before Lifting Impact Your Performance?

TLDR:

• In this crossover trial, researchers looked at whether eating carbohydrates or fasting before a workout helps with resistance training.

• Participants were given either a high-carb meal, a low-carb meal, or a placebo two hours before their workout. The researchers found no major difference in how many repetitions they could do.

• The study suggests that for workouts that focus on the upper body, what you eat right before doesn't really change how well you do.
  
  

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Transcript:

Yo, Dr. Wells here with Nutritional Physical Therapy. I'm here in my jungle of backyard in St. Augustine. Hope you guys are having a great day.

We got a cool research article. This one's for our personal trainers, our sports physios. This one's focused on looking at energy and timing of meals around resistance training.

I know it's been popular over the last probably year or two looking at can I fast and if I do does it improve my exercise outcomes or does it hinder my outcomes? We know some of our data presented in our board approved courses talks a little bit about exercise training low, right? Looking at fasting and exercise and how it can sometimes hinder performance, particularly aerobic performance. It also can affect immunity, right? So we know that it can suppress an immune response. What about resistance training? New research study by King et al in the European Journal of Sports Science.

It's a randomized crossover trial. It was a cool study. Sample size is a little small, 16.

They only do maybe three interventions overall. It's a little smaller study, but it kind of gives us a little bit of insight, right? With this, they do three different sessions. They train basically three sets at 80% of one rep max until failure with four different movements.

One is a back squat. Second is a bench press. The third is a prone row, basically like a bent over row, but maybe laying flat on the bench, and then a shoulder press, right? Some common movements that we see in our fitness related prescriptions or exercise prescriptions for just even the general population, right? So two hours before this session, they drank one of three beverages.

One was a high carbohydrates beverage with 580 calories, dosed at 1.2 grams per kilogram of that person's body weight. The second possible beverage they got was a low carbohydrate beverage with 580 calories at 0.3 grams per kilogram. Again, remember fats have a higher density of calories per gram, so that's why that number is lower.

Regardless, it's isocaloric. And then the third group got a placebo, so it tasted like it had carbohydrates. It tasted like a real beverage, but it had almost no calories.

In the end, what they saw, there was almost no difference in the number of reps that these athletes performed. So the authors concluded that really it didn't seem to matter whether the athlete had consumed something, whether it was high in carbohydrates, high in fat, or nothing at all prior to exercise. The thing that's interesting with this is that, you know, it's basically three different little trials.

So does it really matter, right? Does it really matter if one or two stand out? So really, what is the trend long term, right? It doesn't give us a lot of insights around that. So that's one downside of the study. One noticeable thing is I did see a little bit more of a trend with a little larger effect on lower extremity movements, like back squats.

But unfortunately, again, there wasn't enough, I think, power to really see that difference, and there wasn't enough time to really see that difference. So I'd love to see a study like this done more long term. And we know from other studies that it doesn't typically, like fasting before resistance training or before exercise, doesn't typically affect muscle mass.

But what we do see, particularly in some other studies looking at lower extremity movements like squats and deadlifts, is it can have an impact on the number of reps in some of those other studies for lower body, but not upper body. Now, again, those may be different methods, like the number of reps based on like a lower rep max, so like say 60% versus 80% or one rep max in general. But regardless, it seems that overall fasting doesn't seem to have a major impact on resistance training in the short term.

And as for the long term, we have to wait and see. So come back for more. We have a lot of this stuff in our board approved courses.

Check us out at nutritionalphysicaltherapy.com. Make it a great day.