These amino acids, arginine and lysine, have been found to activate newly discovered brain cells called tanycytes which control the appetite.
Nicholas Dale, professor of neuroscience at the University of Warwick, said: "Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full.
"Finding that tanycytes, located at the centre of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds."
Mackerel is high in amino acids. Photo / Getty Images
Amino acids, found in protein-rich animal products, fruits, vegetables, grains, nuts and seeds, are already known to be the best nutrients for satisfying hunger and keeping us full for longer.
This is because protein is digested more slowly and does not cause the rise in blood sugar which makes us crave more food soon after finishing a meal.
However, it is becoming increasingly apparent that the brain is also important in dieting. Amino acids' effect on the brain would stop people feeling hungry even without any effect on the digestive system.
The key brain cells involved in curbing hunger pangs are revealed in the study led by the University of Warwick and published in the journal Molecular Metabolism.
These brain cells, called tanycytes, rapidly detected the two amino acids found in foods including avocados, almonds and chicken.
The amino acids, arginine and lysine, were quickly detected by brain cells made fluorescent to show their effect.
Within 30 seconds the cells reacted to the amino acids, sending chemical signals which would travel to the part of the brain controlling appetite and body weight.
FUTURE DIET PILLS?
Figs give the natural effect of amino acids. Photo / Getty Images
The findings raise the possibility of future diet pills which could suppress the appetite and help people lose weight.
However they also reveal the natural effect of amino acids in the foods we already eat, which also include aubergines, sweet potatoes, dates and figs.
The tanycytes pick up amino acids using the same receptors in our tastebuds which pick up their flavour. Amino acids have a 'umami' taste, which is the 'fifth flavour' found in many Japanese dishes as well as tomato juice, and tastes meaty and savoury.
When these receptors were blocked, the brain cells no longer reacted to the amino acids.
The study concludes: "It has become evident over the past few decades that the brain is a key player in energy homeostasis, and amino acids can have a satiating effect even when the digestive system is bypassed."
FILLING NUTS COULD REPLACE MEAT AND DAIRY SAYS EXPERT
Pistachio nuts reduce hunger, the study revealed. Photo / Getty Images
People who regularly eat nuts are less likely to be overweight or obese, according to a new study.
Those who consume the healthy snack were found to have a five per cent lower risk of carrying extra pounds compared to those who didn't.
Researchers discovered that participants in their study gained an average of almost five pounds by the end of five years, but those who eat nuts routinely gained less weight.
The study's senior investigator even suggested nuts should replace animal fats.
"Eat nuts during your meal," said Dr Joan Sabaté, the director of the Center for Nutrition, Lifestyle and Disease Prevention at Loma Linda University School of Public Health in California.
"Put them at the center of your plate to replace animal products. They're very satiating."
Interest in a plant-based diet - championed by celebrities including Jared Leto, Gwyneth Paltrow and Mike Tyson - has grown recently as research suggests it is beneficial for heart health and even lowers the risk of certain cancers.
Experts say that vegan diets can be perfectly healthy - but they can cause serious health risks if they are not varied and balanced enough to ensure you're getting all the right nutrients.
THE FOODS THAT REDUCE HUNGER
The scientists discovered two amino acids - arginine and lysine - that react most with tanycytes, the brain cells that control our hunger.
The following foods are high in these acids and are therefore make you feel full:
