Obviously, hunger’s fundamental cause is not eating, but for researchers studying obesity and appetite, the deeper reason is more complicated. The physiological mechanisms that combine to give us a rumbling in our stomachs are complex, and come from our brains, stomachs, hormones and even our environment. Now, researchers in the U.K. have shed light on the matter by showing they can predict hunger with one simple test.
These results provide, for the first time, a biomarker for hunger: a new way to measure and quantify a person’s appetite. The finding will let scientists study the causes and effects of hunger in a more concrete way, opening the door for more fine-tuned recommendations for people working to regulate their appetite for weight loss. (Read more: Do Strong Flavors Satisfy Appetites or Fuel Overeating?)
The study is also relevant to anyone looking for a simple way to feel full longer and avoid those dreaded mid-afternoon cravings. Meals rich in protein, healthy fats, whole grains and vegetables are more likely to keep us feeling full for longer. Eating healthy starts with eating the right amount of food — and what we put in our bodies plays a powerful role in that.
A Simple Blood Sugar Test to Predict Hunger
After you eat a meal, your blood sugar, also called blood glucose, levels rise as energy from your food makes its way into your bloodstream. Your body produces enough insulin (unless you’re diabetic with a compromised or non-functioning pancreas) to bring those blood glucose levels back down to normal levels. But then blood sugar keeps dropping, eventually falling below those levels and releasing hormones telling your body it’s time to eat again.
In a new study, researchers tracked changes in both blood sugar and hunger levels in over 1,000 Brits and Americans (Wyatt et al., 2021). Everyone ate the same breakfast every day for about a week, and then was allowed to eat whatever they wanted for the rest of the day while the researchers tracked their choices.
The researchers found the dip in blood glucose that comes two to three hours post-meal was highly correlated with how much a person ate for the rest of the day. It matched up well with how hungry people reported being, too. People with a greater blood sugar dip felt hungrier, ate lunch sooner, ate more at lunch and even ate more overall over the next 24 hours.
The connection between glucose and appetite had been suggested in the past, but never confirmed. Notably, scientists didn’t expect that the blood glucose dip, rather than the earlier peak, was a better predictor of hunger.
What causes some people to experience a bigger blood sugar dip than others, even after the same meal? That question was outside of the scope of the study, but the researchers suspect it’s at least somewhat related to how high the spike was in the first place. Different people metabolize foods differently, and they say more research is needed to figure out what factors are at play, and how people can regulate these dips on their own.
Keeping Your Appetite In Check
When it comes to weight loss, there’s perhaps no advice more common than “don’t eat too much.” But that advice means different things for different people, and even the most health-conscious eaters can get lost.
Many diets recommend tricks to feel more full after meals without adding excess calories. Drinking a glass of water before meals, eating foods that are more water-rich and less energy-dense, or even drinking caffeinated beverages have all been suggested as dietary hacks. But studies on the effectiveness of these tactics vary.
There is, however, good evidence that eating more protein is a great way to keep your appetite in check, which makes sense considering how protein impacts — or rather, doesn’t impact — blood sugar levels compared to carbohydrates (Greco et al., 2017). For instance, a 2018 study found that adding extra protein to your breakfast keeps blood sugar levels, and hunger, lower for the rest of the day (Kung et al., 2018).
So, protein-rich foods won’t cause the blood sugar spike, and subsequent dip, that sweet and carb-rich foods would. That translates into feeling full longer and craving a sweet snack less often — both of which are a big boost to anyone seeking a healthier diet. And the benefits are likely to extend beyond just feeling full. A recent study of older adults suggests low-carb diets do appear to be uniquely effective for weight loss (Goss et al., 2020). And contrary to what some nutritionists claim, such diets do not appear to harm kidneys.
That doesn’t mean you need to start measuring your blood glucose levels with an at-home blood sugar test. But we can all take something away from this latest research into blood sugar and appetite. Some foods, like sweets and refined carbs (think: white bread and French fries), cause blood sugar to rise higher and faster. These are referred to as having a high glycemic index.
Low-glycemic index foods, on the other hand, have a lesser effect on your blood sugar levels, and that makes them better options for you. Fish and seafood of all kinds, meats, eggs, low-sugar fruits (like blueberries, raspberries, and strawberries), and fats such as olive oil, as well as whole grains, beans and peas, non-starchy vegetables and dairy products are all good options for meals that are filling and that don’t cause “crashes” later on.
So load up on healthy proteins like seafood, natural, hearty grains and fresh fruits and vegetables for breakfast. You’ll thank yourself come dinnertime.