Do you ever find yourself a few minutes into a workout or a cycle ride and you come over shaky? Or you start really sweating? Or your heart starts beating really fast? But yet, you haven’t started to excerpt much energy. If that is the case, you could be experiencing reactive hypoglycemia. Or, in simpler terms, a spike in glucose levels from having recently eaten before exercising. This is something that doesn’t just happen in those with diabetes.
A recent study conducted by the European Journal of Sports Science and Supersapiens found that 15% of those who participated in the research experienced reactive hypoglycemia from eating before a workout, especially when eating between 30 to 90 minutes before exercise. While the research suggested this did not have an impact on a person’s athletic performance, it is not a nice experience.
“The good thing is that it is transient,” Kristina Skroce, sport physiologist at Supersapiens, told Rouleur. “As most people are healthy and have a well-functioning body, the reactive hypoglycemia will pass, but it can last up to 20 minutes.”
She is quick to state that this is very individual and many factors can contribute towards whether you experience this or not, such as the type of exercise you are undertaking, the meal you had beforehand, the carbohydrates included in this, and timing. All of these factors come into play, causing “a mess” she said, if you are susceptible to this.
The research conducted by Supersapiens however, is not able to yet uncover what makes a person sensitive to reactive hypoglycemia. “There are too many variables,” said Skroce. “You’re unable to say, if you are tall, skinny, male, ride your bike eight hours a week, and your glucose level is this, then you’re going to experience it. Unfortunately, that is not possible, but we can generalise what we saw from the results, and inform people of this tricky eating window.”
Image by Supersapiens
The key thing that Supersapiens team discovered was this tricky food timing window pre-exercise, and this is something they suspected to be true but did not have access to such a large data pool with minute-by-minute data. Most research on this subject have mainly been lab-controlled experiments, but by people using Supersapiens' continuous glucose monitors (CGM) every minute of every day to track their glucose levels, the team at Supersapiens were able to take the research out of the lab - proving that eating pre-exercise between the 30 to 90 minute window can cause reactive hypoglycemia in healthy, athletic people.
“You will feel the symptoms straight away,” she said, in regards to those who eat within this window and are prone to experiencing this. “Imagine you ate something 45 minutes before your training, so you started training 45 minutes after that food ingestion, you’re going to have a peak in insulin.
“So, at the time you start exercise, your glucose uptake will rise and your insulin is then dropping your glucose. And this is why you’ll then have the shakiness, sweating, fast heart rate and tiredness.”
Skroce informed that it is carbohydrates, whether starchy or from sugars, that cause a person’s glucose to rise, so finding the optimal time to eat before exercising is crucial for many people. But carbohydrates are also a good source of fuel and that is why eating them over the 90-minute window will ensure that a person doesn’t suffer from the not-nice symptoms which come with reactive hypoglycemia. The study also highlighted that eating right before exercise will also prevent this, but Skroce noted that it is best to base these meals around proteins and fats, like eggs, bacon, and avocado, to flatten the curve, saving a carb-based meal for after training.
Supersapiens work with many athletes across different sports, at different levels, so understand the importance of performing and feeling at absolute peak performance when lining up for a race. “I advise all athletes to eat at the two to three-hour mark before a race. That way your body has time to do everything it needs to come back to normal balance,” she said.
But many are not high-performing athletes, most people enjoy cycling as a hobby, and that, more often than not, includes a cafe ride. Cake, pastries, sandwiches – it’s a true carb-fest. And people might be eating and riding again in that 30 to 90 minute window. “Again, it is individual,” she said. “But it can happen, of course. I myself have been using CGM for a few years now, but I am not restricting myself.
“It is not about saying this food is good and this one is bad, it is about understanding optimal timing and where I will be causing myself the least damage if I am prone to reactive hypoglycemia. Sometimes the goal of the ride is the cafe, so we don’t want to take that social element away. It is just, if you are riding everyday, you might want to consider what you are eating a bit more because it might be tricky to manage this all the time in training.”
Reactive hypoglycemia, or the sudden drop in blood sugar levels following a meal before exercise, can catch many off guard, whether they’re an athlete or a casual enthusiast. And this recent research by Supersapiens sheds light on the importance of timing when it comes to pre-exercise meals, finding that sweet spot where people can enjoy their rides to the fullest.
*Cover image by Getty Images