A study has shown that strict diets are always doomed to fail, because certain neurons in the human brain react against your brave diet-attempts.
The culprits who ruin our dietary plans are the so-called AGRP-neurons, cells that are very sensitive to hunger. These cells cause unhealthy but tasty foods to become irresistible to us when we're hungry. The AGRP-neurons immediately become active when our stomach growls and there is food nearby. And food is always nearby in our society. So saying: "it was stronger than I was", is not completely untrue when you still reach for a chocolate bar while you had promised yourself to live on salad and water.
Hungry? That means you want to eat
An earlier research discovered that we like to eat because certain neurons give us a good feeling if we eat when we're hungry. That's why our meal tastes better when we're really hungry, which has led to the proverb: "hunger is the best sauce". The AGRP-neurons do the exact opposite. They make us experience hunger as a negative feeling, which leads to us avoiding that feeling by eating.
Motivation to go look for food
Like with many other things, we have our ancestors to thank for this once useful reflex. Experiencing hunger as a negative feeling motivated our ancestors to go look for food in the dangerous wilderness, forcing them to make an effort to survive. Nowadays, we no longer have to look for food in a dangerous environment, and food is for the taking everywhere you look. Unfortunately, our cells still work the same way, and because of these AGRP-neurons we wish to avoid hunger at all times. Therefore, those who start with a starvation diet are in for rough times. Sooner or later, that underlying instinct will make you reach for whatever food is within reach, regardless of what is available at that time.
Don't follow strict diets, but eat healthy
In the future, scientists will be able to switch off these AGRP-neurons, since they are no longer necessary. But while we wait for that, there's a much simpler way to maintain your healthy eating habits: avoid strict (crash) diets, which lead to awful hunger and can cause a yo-yo-effect. Instead, pick a healthy eating pattern with lots of vegetables and fruit, so that you won't be hungry. And allow yourself a little extra from time to time.