Can Exercising Before Breakfast Dramatically Improve Your Health?

Hot on the heels of National Diabetes Month, a new study has shown that exercising before eating breakfast can improve how your body responds to insulin.

Brock Armstrong
5-minute read
Episode #464
The Quick And Dirty

Researchers at the University of Bath performed a six-week study on 30 men and discovered that eating breakfast after a period of moderate-intensity exercising had no effect on weight loss but had a "profound impact on overall health," including lowering insulin resistance. 

Eating after a 60-minute workout a few times a week could be beneficial, particularly if you're concerned about your blood sugar levels.

I know National Diabetes Month is all but over but I couldn't let it pass completely without taking a look at one potentially easy way to aid in the fight against this troublesome condition.

In a new study, published in the Journal of Clinical Endocrinology and Metabolism, health scientists at the Universities of Bath and Birmingham set out to assess the acute and chronic effects of exercise performed before versus after nutrient ingestion (or breakfast, as us non-scientists call it) on whole-body and intramuscular lipid utilization (or fat burning), and postprandial glucose metabolism (or insulin sensitivity).

The six-week study was performed on 30 men who had been classified as obese or overweight and compared results from three groups:  

  1. One group who ate breakfast before exercising
  2. One group that ate after exercise
  3. A control group who made no changes to their lifestyle

No effect on weight loss

Let me point something out right off the bat. Whether the men in this study ate their meal before or after exercising didn't make any differences in terms of weight loss over the six-week testing period. But the timing of meals did have "profound and positive" effects on their health.

I think this is an important point to make. There is a notion in the wellness-sphere that by exercising in a fasted state, you will literally burn the fat off of your body. While the researchers did find that the subjects used more of the fat from their fat tissue and the fat within their muscles as a fuel, it did not result in some magical weight loss protocol. 

Whether the men ate their meal before or after exercising didn't make any differences in terms of weight loss but it did have "profound and positive" effects on their health.

The subjects who exercised after eating breakfast lost the same amount of weight as the hungry exercisers who ate it after. And not surprisingly, the group who didn't change their lifestyle at all lost no weight. 

Meal timing

There have been a growing number of studies and hypotheses that involve interventions like intermittent fasting, multi-day fasting and simply adjusting meal timing, in general, to help control blood sugar and potentially turn you into what has been called a "fat burning beast."

Monica Reinagel, the Nutrition Diva, wrote about the state of intermittent fasting research in and article called Does Intermittent Fasting Work?

A lot of the current excitement about intermittent fasting is still based on some of those early animal studies, which found that intermittent fasting led to weight loss, improvements in body composition, blood-sugar metabolism, and other exciting things—even though the rats were eating the same amount of food! Unfortunately, the human studies haven’t been quite so dramatic.

Monica Reinagel, Nutrition Diva

Intermittent fasting, or eating within a restricted time window, does tend to lead to weight loss, but it's usually because people following these regimens end up eating less daily. And while these approaches can result in body composition, cholesterol, and blood sugar metabolism improvements, so can pretty much any weight loss approach. The magic doesn't necessarily reside in what time of day you eat.

Exercise timing

Meanwhile, in this exercise study, the results were indeed observed in humans, not just rats. The difference between the before- and after-breakfast exercisers was pronounced. 

Lead researcher, Dr. Gonzalez, said in an article at the University of Bath: "The group who exercised before breakfast increased their ability to respond to insulin, which is all the more remarkable given that both exercise groups lost a similar amount of weight, and both gained a similar amount of fitness. The only difference was the timing of the food intake."

Changing the timing of when you eat in relation to when you exercise can bring about profound and positive changes to your overall health.

He went on to say that these results suggest that changing the timing of when you eat in relation to when you exercise can bring about profound and positive changes to your overall health.

We found that the men in the study who exercised before breakfast burned double the amount of fat than the group who exercised after. Importantly, whilst this didn't have any effect on weight loss, it did dramatically improve their overall health.

Dr Javier T. Gonzalez, Department for Health, University of Bath

What I found surprising was that over the six-week trial, the scientists found that the group of men who exercised after breakfast ended up being no better off in the insulin department than the control group who made no lifestyle intervention at all. 

Exercising before breakfast—the study facts

At the laboratory, both groups consumed a standardized breakfast of cornflake cereal with skimmed milk, wholemeal toast, sunflower spread, and strawberry jam. This rather British-sounding breakfast was specifically calculated to provide 25% of the participants' estimated daily energy requirements and was made up of 65% carbohydrate, 20% fat and 15% protein.

The breakfast-then-exercise group

After this group finished eating and allowed themselves a 90-minute rest-and-digest period, these participants cycled on stationary bikes for 60 minutes. The exercise was categorized as "Moderate-intensity," or 65% of the subject's peak oxygen uptake (or V̇ O2 peak). 

The exercise-then-breakfast group

This group completed the same protocol. The only difference was that their breakfast was consumed immediately after 60 minutes of moderate-intensity cycling. 

Both groups had exhaled breath samples collected through oxygen masks—they're similar to those you see on hospital TV shows, but they work in reverse. The samples were collected at 25-30 min and 55-60 min of exercise to determine "whole-body substrate utilization rates," or which fuel or fuels were being used to power the cyclists. The researchers also did blood tests at regular intervals during the workout and over the next several hours.

The data were tabulated, correlated, and verified. The results were published in the Journal of Clinical Endocrinology and Metabolism for the world to see. 

Should you exercise before breakfast?

Exercising before breakfast sounds easy, and it is. But even though it's easy, it is not necessary for all of us to do, and certainly not daily. 

If you're unhappy with the direction your blood tests are headed, this is a strategy you and your doctor can discuss. If diabetes runs in your family and you want to be proactive about your blood sugar, doing this type of workout once or twice a week could be a good idea. 

60-minutes of moderate-intensity movement is all it takes.

And please, keep in mind the duration and intensity of this workout. 60-minutes of moderate-intensity movement is all it takes. Don't head out the door with an empty stomach every single day to crush a high-intensity 90-minute WoD (workout-of-the-day). 

In the article for the University of Bath, co-author of the study, Dr. Gareth Wallis added: "This work suggests that performing exercise in the overnight-fasted state can increase the health benefits of exercise for individuals, without changing the intensity, duration or perception of their effort."

He then went on to say, as researchers often do. "We now need to explore the longer-term effects of this type of exercise ..." and, much to my relief, he also added, "... and whether women benefit in the same way as men." 

About the Author

Brock Armstrong

Brock Armstrong is a certified AFLCA Group Fitness Leader with a designation in Portable Equipment, NCCP and CAC Triathlon Coach, and a TnT certified run coach. He is also on the board of advisors for the Primal Health Coach Institute and a guest faculty member of the Human Potential Institute. Do you have a fitness question? Leave a message on the Get-Fit Guy listener line. Your question could be featured on the show.