Science finally explains why you’re hungry 24/7

We all have that one friend who’s ready and willing to eat again after eating just an hour or two earlier. Perhaps you are that friend. In either case, a new study just released by King’s College London appears to have finally figured out why certain people are seemingly hungry all the time.

In a nutshell, the findings all come down to blood sugar levels. Study authors say some people experience a much bigger drop in blood sugar just a few hours after eating than others. These individuals reported generally feeling hungrier throughout the day, spending less time between meals, and eating more in general.

“It has long been suspected that blood sugar levels play an important role in controlling hunger, but the results from previous studies have been inconclusive. We’ve now shown that sugar dips are a better predictor of hunger and subsequent calorie intake than the initial blood sugar peak response after eating, changing how we think about the relationship between blood sugar levels and the food we eat,” says Dr. Sarah Berry from King’s College London.

All in all, the research team believes their work hammers home the fact that personal metabolism influences eating and weight outcomes just as much as diet and exercise. Just because two people eat the exact same meal, that doesn’t mean their bodies will react in the same way.

The most important aspect of the experiment that produced this study is that all participants ate a standardized breakfast. That way, study authors were able to observe how different peoples’ bodies digested the same meal. 

In total, 1,070 people took part in this work, and for two full weeks, after they had eaten their uniform breakfast individuals were free to eat whatever they wanted the rest of the day. By the end of the observation period, 8,000 breakfasts and 70,000 meals in total had been consumed. Subjects also underwent a fasting blood sugar response test to determine how efficiently their body processes sugar.

During the entire duration of the observation period, participants constantly wore a continuous glucose monitor (GCM) to assess blood sugar level changes throughout the day. Other monitors tracking sleep and physical activity were worn as well. Finally, hunger, alertness, and time of each meal were tracked via a phone app.

Most earlier studies focusing on blood sugar changes have only studied what happens one to two hours after a meal. This time around researchers expanded that period to two to four after eating. This adjustment helped them notice that some people experience “significant sugar dips” two to four hours after the initial peak seen just after eating. In these cases, the dip even fell below baseline levels before rising back up.

These subjects, dubbed “big dippers” by researchers, showed a nine percent increase in hunger and waited about a half-hour less than others before their next meal. Moreover, big dippers also ate an average of 75 more calories during the three to four hours after breakfast and roughly 312 calories more over the entire day than other study participants. If this pattern is applied to a full calendar year, it represents a potential weight gain of 20 pounds.

“Many people struggle to lose weight and keep it off, and just a few hundred extra calories every day can add up to several pounds of weight gain over a year. Our discovery that the size of sugar dips after eating has such a big impact on hunger and appetite has great potential for helping people understand and control their weight and long-term health,” comments study leader Professor Ana Valdes from the School of Medicine at the University of Nottingham.

Importantly, when other factors like BMI, age, or body weight were considered there didn’t appear to be any correlations between blood sugar tendencies. All of these findings suggest, researchers say, that one’s metabolism will ultimately determine their blood sugar fluctuations.

“Food is complex and humans are complicated, but our research is finally starting to open up the black box between diet and health. We’re excited to have been able to turn this cutting-edge science into an at-home nutrition and microbiome test so that everyone has the opportunity to discover their unique responses to food to best support their metabolism and gut health,” explains Tim Spector, Professor of Genetic Epidemiology at King’s College London and scientific co-founder of ZOE, a health science company that helped author this research.

If you think you may fall under the “big dipper” category, it’s still quite possible to find a diet that will leave you feeling satisfied – it just may take a bit longer before you find the right recipe for success.

“This study shows how wearable technology can provide valuable insights to help people understand their unique biology and take control of their nutrition and health. By demonstrating the importance of sugar dips, our study paves the way for data-driven, personalized guidance for those seeking to manage their hunger and calorie intake in a way that works with rather than against their body,” concludes lead study author Patrick Wyatt from ZOE.

The full study can be found here, published in Nature Metabolism.