September 23, 2022
Jessica Bradley, BBC Future
Some foods promise to cut cravings. Can any food actually suppress our appetite?
Your weekly groceries are likely to be filled with packaging promising that the food they contain will taste good, stay fresh, and be good for you. You may also find products that tell you they will keep you feeling full longer. But is it really possible for a food to suppress our appetite?
While some research suggests that eating certain foods, like chili peppers and ginger, can make us feel less hungry later, these studies often use large amounts of food and test the effects on animals, says Gary Frost, from the Imperial Nutrition and Food Network at Imperial College London. Transposition of these effects to humans has not occurred, he adds.
One study, however, looked at the appetite suppressant properties of capsaicin in chili peppers (the active ingredient that gives chili peppers their heat) using amounts that more closely resemble an average human diet.
Mary-Jon Ludy, associate professor of food and nutrition at Bowling Green State University in Ohio (USA), first experimented at home, adding chili to her meals until she decides how much is acceptable and realistic for someone living in the American Midwest.
She then invited 25 people to her lab six times, and gave them bowls of tomato soup.
After the soup, they remained in the laboratory for four and a half hours so that their appetite and energy expenditure could be regularly measured.
They were then served another meal and told they could eat as much as they wanted.
When they consumed a soup containing 1 g of chili, participants burned an additional 10 calories over the next four and a half hours.
Participants who used to eat chili only once a month reported having fewer thoughts about food afterwards, and ate 70 fewer calories when they were served the second meal, per compared to those who used to eat chilli three times a week or more.
Ludy conducted the same experiment with chili in a capsule instead of the soup, but the increase in fat burning was only seen after eating the chili-tomato soup.
“That means the tingling and burning sensation in the mouth is significant,” she says.
However, burning 10 extra calories after a spicy meal is tiny and won’t have long-lasting effects. Frost points out that studies like this, which show short-term effects on appetite, haven’t been able to show long-term effects.
Consistent with this study, a review of 32 studies found that chili peppers, as well as green tea, were not consistently found to suppress appetite.
Coffee is another staple in our diet that is rumored to make us feel less hungry. Matthew Schubert, an assistant professor in the Department of Kinesiology at California State University, reviewed the research conducted so far to determine whether coffee may have an appetite suppressant effect.
Some studies have shown that drinking coffee slightly speeds up gastric emptying, which is the time it takes for a meal to move from the stomach to the small intestine and is associated with increased hunger. But no studies have shown that there is anything specific physiologically going on that can reduce appetite.
Fiber is known to make us feel full longer.
Even if future research points to a way that coffee suppresses appetite, it would likely only translate to consuming 100 or 200 fewer calories per day, Schubert adds, which isn’t significant.
Besides the specific ingredients, the researchers also looked at macronutrients and how they can influence our appetite. Fiber is known to make us feel full longer, and some population studies show that the more fiber people eat, the slower their weight gain is – but this only happens when they consume very high amounts of fiber, said Frost.
“It is recommended to consume 30 grams of dietary fiber a day, but most Britons consume around 15 grams. If you go up to 30g, you get an effect [sur l’appétit]but it fades after a while,” he explains.
Eating more protein has been found to decrease appetite, but this was only seen in a very small trial.
A lot of research has been done trying to figure out which macronutrients make you feel fuller, but there’s no clear answer.
The results seem to indicate that protein is more likely to fill you up, but they are not very clear and the effects are generally tiny, and it is difficult to compare the different types of macronutrients “, explains Yann Cornil, associate professor of marketing and in behavioral science at the University of British Columbia in Vancouver, Canada.
Instead of looking for specific foods to curb our appetite, we should make sure we’re drinking enough water, because water briefly interrupts our appetite, says Martin Kohlmeier, professor of nutrition at the Gillings School of Global Public Health in Carolina. North (USA).
Research has shown that people who drink two glasses of water before eating end up eating less.
If there was a food component that suppresses the appetite, to survive it would have to be avoided altogether. – Gary Frost
But any change in our appetite at the physiological level will be small and short-lived, Frost says, because it doesn’t make physiological sense that there is a food that causes us to eat less.
“It’s only very recently that our Western society has experienced an excess of food,” says Frost. Throughout evolution, we have lived on very little food, and it has come in spurts. Our physiology is designed to drive us to eat.
“If there was a dietary component that suppresses appetite, to survive it would have to be avoided altogether.”
Another reason why no food or drink could substantially suppress our long-term appetite is that our bodies are designed to maintain near-constant weight, Kohlmeier says.
“The body has mechanisms that defend weight in a vicious way. From an evolutionary standpoint, the greatest risk to humanity was starvation, not only because it kills you, but also because it weakens the body and makes you more susceptible to infectious diseases,” he explains.
The system the body uses to regulate the amount of food we eat is one of the most complex systems in the body, adds Kohlmeier.
“If you see the body as a big machine, with all the different components that have to come from outside; you have to have enough water, macronutrients and micronutrients, in addition to knowing what not to eat.”
There are several nutrients that will stimulate our appetite if we are deficient in them, he adds.
“It’s a whole system that you have to loop and constantly rebuild. How could someone know what they need and what is in this or that food? There are very powerful important systems in place that stimulate the appetite.”
Hunger is determined by beliefs, expectations and memory.
Therefore, the best way to manage appetite is to eat a balanced diet, so that the body is not pressured to eat more to compensate for any deficiencies, says Kohlmeimer.
The loophole here is how our appetite can be influenced psychologically, something that has interested researchers for decades. A 1987 article explains that the sight and smell of food send signals to the body to prepare it to digest it.
According to this article, foods have the greatest effect on appetite when we expect them to fill us up.
According to Mr. Cornil, hunger is determined by beliefs, expectations and memory, and above all by the fact that we remember well what we have eaten. This means that we eat less after what we perceive to be a larger meal than if we believe we have eaten a smaller one.
A study has found that labeling a meal as “full” prompts us to eat less than when the same meal is labeled as “light”.
Your weekly groceries may contain foods that promise to keep you full longer, but there seems to be only one way to work with your body’s evolving processes: eat a balanced diet containing all the nutrients and water you need.
While you can’t cheat nature and stave off hunger for long, you can try to avoid craving those extra calories needed to make up for any nutrient deficiencies.