A while back I was watching one of my favorite programs – Come dine with me. (I know its sad, but it is so entertaining. ha) Anyway, it was the couples come dine with me. And there was a “fit” couple who was hosting the dinner party. This couple was eating a healthy lifestyle and wanted to show their guests that eating healthy didnt necessarily have to be boring. On the top of my head I can’t remember exactly what all the three courses they served was, but it was fairly low in starchy carbs, loads of good lean source of protein and vegetables.
At the end of the program their guests was commenting about how the meals was, and to my surprise they said they all left with the feeling of still being hungry. And that got me thinking; they have all consumed a three course meal and they still feel hungry? That can’t be right, can it? Then I was thinking of when I eat lean foods vs normal foods. I do indeed feel a difference in how I feel, how my stomach feels and an overall different feeling of satisfaction.
Let me put it in better perspective for you:
If im on a competition diet or just eat normally healthy, after my meals, I feel satisfied, my stomach is flat and I do somehow feel like I could eat more, but then Id probably feel slightly bloated or just stuffed.
If I eat such as pizza, Id feel full, Id be a bit bloated – my stomach wouldn’t be flat and I would not want to eat more food.
So can this be a reason why people fall off eating healthy or being on a diet? As they think after they have eaten a meal that is nutritious, they don’t feel the way they used to feel while eating the way they used to? Do they have a misled feeling of what actually satisfaction feels like?
So taking hunger from a biological point of view: (If you are not interested in the science behind this, jump down to the half bottom of the page)
What is really hunger? The sensation of hunger is really a balance of hormones and chemicals. This balance has two sides: hunger and satiety.
Hunger and satiety are crucial regulatory mechanisms that contribute to maintain a healthy bodyweight or to disrupt it. Both hunger and satiety are operated in the brain, in the hypothalamus, although there are also other parts of the brain that are also involved. Hunger is controlled by the lateral hypothalamus and satiety in the ventromedial hypothalamus. Both works pretty similar, if stimulated it will give you the feeling of feeling hungry or the feeling of feeling satisfied. And in fact if either to be damaged you would never feel hungry or satisfied again!
Hunger is our biological drive to eat. When our digestive system and our energy stores are beginning to run out of energy and nutritents they send signals that it is time to eat and a group of chemicals called orexins is released into our bloodstream. The main orexin – Neuropeptide Y is released into our brain when we run out of energy and nutrients and that causes us to feel hungry.
When we have enough nutrients and energy, other chemicals are produce such as alpha-melaonthropin – which then will be released in our brain causing satiety.
Appetite is our psychosocial drive to eat and are mainly controlled by external influences but is also controlled by endorphins. What we eat, when we eat, where we eat, why we eat and how much we eat is our eating behaviours. Its determined biologically, psychologically and socially.
Now lets look at satiation. Satiation is the perception of fullness which develops during a meal and determines its duration. In short-term end of meal signals are both psychological, mechanical and hormonal. The main psychological signal is our perception of the amount of food we have eaten. Our brain mainly takes the volume of food and the number of servings and not so much the caloric density or the nutrient content. The main mechanical signal is the distention of the stomach and intestinal walls caused by the presence of food. The two important hormonal signals are the release of CCK and PYY3-36 which inhibit the release of Neuropeptide Y(the hunger signal).
Now satiety is the perception of fullness after the end of the meal and determines the interval until next meal. Sensors in our brain and liver are constantly measuring glucose and insulin levels, and when these are low, our liver starts gluconeogenesis to make some new glucose and our brain induces hunger to get some more from food. Our stomach and intestines also have a role to play – when the stomach is empty it releases Ghrelin and it induces hunger via Neuropeptide Y release.
Now the nutrient content of our foods does have an effect on our hunger and satiety signals. Some nutrients are more satisfying in the short-term(satiation), while other long term(satiety).
Fiber is stong on satiation but not so much on satiety. Lipids has weak satiation but strong on satiety. Carbs is somewhat good on satiation but weak on satiety. And protein is strong on both satiation and satiety.
So just by looking at this you can see that what your meals consists of, it will have a massive impact on your feeling of hunger and satisfaction.
But we also have to take leptin into context. Leptin operates in the longer term of satation and satiety. Leptin is a hormone secreted by the adipose tissue(body fat) and it targets the brain to decrease hunger. And its variation regulates hunger in the long-term. Leptin signals to the brain and it gives a homeostatic regulation, so if the adipose tissue increase, leptin increases and hunger decreases. If the adipose tissue decreases, leptin decreases and hunger increases.
Although the brain can get overexposed to leptin and become leptin resistant(insensitive to leptin) – which means you will have no feeling of satiety. This is why overweight or obese people don’t know when to stop eating as the brain can’t respond to the high leptin levels(although a small % of people became obese because they already had a lack of leptin levels). Also high leptin levels in the system is actually harmful as it has pro-inflammatory effect.
Another kind of stop eating signal is specific satiety, which mostly determents the composition of our meal than its duration. Specific satiety is the perception of fullness that develops when eating one specific food. If we keep eating one specific food, lets say apples, our hunger for apples will decrease although we will still have appetite for other foods. Say if I ate 3 apples, I probably didn’t want to eat another one, although if you offered me an ice cream Id probably eat that. This mechanism is good to make sure we get a varied diet and its also used as a trick in many popular weight loss diets – they don’t restrict the amount of the foods, but cut other foods. Causing you to eat less food and calories as you get ‘fed up’ with the foods(such as soup diets etc).
So back to my question on the beginning of this post. Yes, I do believe most people do have a somewhat wrong perception of what actually satiety and satiation actually feels like, and I do believe this comes down to people don’t listen to their bodies. But hey, I’ve been a victim of this as well. And of course I don’t always listen to my body, sometimes I simply just want to eat that whole pizza just because I want to.
Whats your thoughts? Do you think you know when you actually feel satisfied?