Same Food Leads to Different Effects in Different People

woman having breakfast

Have you ever gone on a diet with one of your friends and noticed that they seem to get better results than you? How about switching the food you eat to stave off diabetes or weight gain, only to find that it didn’t help with either? A new study published last week found that your experience may not be so unique. The researchers set out to understand how different people digest different types of food, and their results reveal why food recommendations that make sense for some may not work so well for others.

What makes food healthy or unhealthy?

This question has been hotly debated for centuries. One way to approach it is to think about whether the foods cause illness, either immediately or in the long term. For example, we think of eating raw eggs as unhealthy because it can make you sick in the short term. Red meat is thought of as unhealthy because it can lead to heart disease and cancer in the long term. On the flip side, we can also think of healthy foods as those that tend to prevent disease. Many vegetables, for example, have been found to lower the risk of cancer, heart disease, and a variety of other illnesses that shorten people’s lives. The problem is, whether a food prevents or leads to disease isn’t always clear. The effects on health can be small and may take a long time to show up. On top of that, researchers and physicians have observed that people respond differently to food based on their own unique makeup and the health problems they might already have. This research team wanted to figure out how this unique makeup might affect which foods qualify as “healthy” for individuals.

How does blood glucose play a role?

In deciding which foods are healthy or unhealthy, it’s important to look at how the body responds to various foods. Blood sugar levels have become indicators of health in medicine because they’re associated with one of the most widespread diseases in America today: diabetes. Blood sugar is supposed to rise when you eat food as it gets broken down into sugars, proteins, and fats. But the body should be able to keep those levels within a healthy range. In diabetics, those levels skyrocket because the body isn’t able to effectively use that sugar because the signals that control sugar levels aren’t working properly. Even in healthy people, though, sugar can get pushed into the high zone by certain foods like sweets that are high in simple sugars. The research team wondered if blood sugar levels soared equally when these unhealthy foods were eaten, or whether some people had an easier time keeping their blood sugar levels within the normal range.

How did the researchers test food responses?

The team recruited 700 healthy people between 18 and 70 years old free of diabetes and connected them to a continuous blood glucose monitor that they could wear around 24 hours a day. They had the participants log when they were exercising, eating, and sleeping. They also logged all the foods they were eating. Each participant followed their usual daily routine except that the first meal of the day was one of four standardized meals made by the research team. In total, the researchers had almost 47,000 glucose measurements by the end of the study. The researchers also did blood tests and gathered data on the type of bacteria living in the gut of each participant. They pooled all of this data together and looked for patterns in the foods people were eating, the types of gut bacteria they had, and what their blood sugar was at any given time.

What did the researchers find?

When all the data was analyzed, the team found that different people had very different blood sugar measurements even after eating exactly the same foods. Some people eating foods that might have been considered healthier saw their blood sugar levels spike, while others eating the same foods had no issues. The standardized meals provided the best evidence of this since everyone ate similar meals for the first meal of the day, but often responded differently.

To get a better grasp on what was going on, the team wrote a mathematical algorithm to try and model what a person’s blood sugar would do in response to food based on various data the team had collected. Once they’d made the model, they recruited 100 more participants to go through the same study, except this time they used their algorithm to try and predict how they would respond to various foods based on their unique makeup. They found that their model was more successful in predicting what a person’s blood sugar would be after eating certain foods than whether or not the food was considered healthy. In looking over the model, they found that blood sugar levels were influenced by the food a person had just eaten. More often blood sugar reflected things like what people ate at their last meal, how recently they had slept, how recently they’d exercised, and what bacteria they were carrying in their gut.

What does this mean for me?

This research shows that what makes up a healthy or unhealthy diet is probably more nuanced than we thought. What might work well for one person may not be so good for another. The hope is that research like this will help healthcare providers design plans that will work better to achieve a person’s health goals than one size fits all guidelines. That doesn’t mean that you should throw out your carrots and hit the brownies. But if you’ve changed your diet and it doesn’t seem to be having the health effects you were hoping for, you might want to try changing course to see if you can find something that better matches your metabolism.