Understanding Your Appetite: Part 2

Should you trust your tummy instead of counting your calories? Today, we pick up where we left off as we get to know our appetite and explore the signals of hunger.


Fullness Factor

Does eating a large bowl of soup or guzzling water really trick your hunger into going away? Factors commonly thought to influence satiation include fibre content, total calories, the bulk of food, the speed of eating and drinking, the weight of the food or beverage and amount of protein, carbohydrate or fat in a meal.

A recent study showed that calories may be the bottom line in achieving satiation, rather than any of the factors listed above. Researchers compared hunger ratings after subjects had consumed a variety of foods at different times. They found that hunger ratings were lowest after subjects consumed 500-calorie food portions, such as chocolate and peanuts, compared to equal weight or volume portions of low-calorie foods.

What about the bowl of soup or glass of water technique where you finish them in one sitting before commencing your main meal? Researchers claim that these are not effective cues to satiation. The bottom line is that if you have not had enough calories, your hunger will return quickly.


The Force of Culture

Before we get too far into the physical effects of different foods, it is important to focus on the massive impact that culture has on food intake. Over the past few decades, a few notable cultural changes have occurred:

  • Beverages contribute to an increasing number of calories
  • Portion sizes have increased
  • Lifestyle activity has decreased

Such factors are bound to increase your calorie intake and decrease calorie expenditure. Moreover, due to the subtle changes in our diet, we are now consuming a mix of foods that exert a weaker effect on our satiety mechanisms and, as a result, we passively overconsume on a chronic basis. A diet high in fat, low in fibre and high in fluid calories rather than solid calories does not provide effective cues to regulate hunger and satiety. That basically means you will eat more without even realising it.

In addition, social factors can also override physical hunger. Office birthday parties, family dinners, champagne toasts and holiday gatherings — all these occasions revolve around eating and drinking, so it is hard to abstain from that social pressure. You can also tack emotional eating onto the list of outside forces affecting our food intake. You may mistake boredom or frustration for hunger, or associate a happy time with sweet food. If you grew up in an environment in which dinner was always followed by dessert, you may not feel like a meal is complete until you have something sweet. Are such cravings surmountable?

Some researchers suggest that a lack of the hormone serotonin may drive an actual physical need for carbohydrates. Evident human appetites for sugar and fat have led to suggestions that macronutrient consumption is directly mediated by the central nervous system. The problem is that cravings actually revolve around specific foods rather than carbohydrate or fat. For instance, someone might crave for a cookie but not a baked potato, even though the potato is much higher in carbohydrate.


Foods Are Metabolised in A Hierarchy

Many people believe that fat is the most satiating form of food as it delays gastric emptying. Contrary to popular belief, fat may be the least satiating. Our bodies maintain great quantities of fat, moderate quantities of carbohydrates and limited quantities of protein as energy stores. In a very simplified model, when we eat protein, most are used for non-energy needs, such as repairing tissue, and the small balance is used for energy rather than being stored.

Carbohydrate comes next. Because the body’s storage capacity is about equal to a day’s intake, it presents a strong signal that influences satiation. However, since we can store so much fat, it does not need to be metabolised immediately. Fat provides a weak signal that fails to result in prompt termination of eating. Basically, fat has a weaker effect than protein or carbohydrates. Fat may be problematic because it is so calorically dense. Eating 500 calories of potatoes will feel very different than downing 500 calories of chocolate because of the vast difference in the volume of food with each of these portions. It is easy to overcome fat before any satiation mechanisms come into play.

One element of confusion is thinking that if your stomach is full, you are no longer hungry. This leads to the practice of filling up the stomach with water, broth soups or low calorie, high volume foods like popcorn or rice cakes. To tame your hunger and control your eating, you must understand that many factors make the body “turn off” hunger, including nutrient receptors in the intestinal tract, nutrients in blood, various hormones and stomach distention.