Digestion and satiety

Together, the stomach and intestines are known as the gastrointestinal (GI) tract. The food you eat passes into this digestive system, where it is processed both mechanically and chemically until it is broken down into small, easily-absorbed fragments.

It is here that carbohydrates are disassembled into simple sugars such as glucose and fructose, most fats are dismantled into fatty acids and monoacylglycerols, and proteins are pulled apart to become amino acids.

Your body then absorbs these basic nutritional units, along with any micronutrients that are present, such as vitamins and minerals. The whole operation of digestion is regulated by signals passing to and fro along the pathways of your enteric nervous system, as well as various hormonal and other chemical signals produced by cells lodged in the lining of your gastrointestinal tract.

Gastrointestinal satiety signals.

Gastrointestinal peptides are synthesized in certain areas of your brain, as well as being manufactured in your GI tract.

Steven Woods, doctor of Physiology, Biophysics and Experimental Psychology in the USA writes, “. . . when food is eaten, it interacts with receptors lining the stomach and intestine, causing the release of peptides and other factors that coordinate the process of digestion with the particular food being consumed. Some of the peptides provide a signal to the nervous system, and as the integrated signal accumulates, it ultimately creates the sensation of fullness and contributes to cessation of eating.

“Although dozens of enzymes, hormones, and other factors are secreted by the GI tract in response to food [inside the GI tract], only a handful are able to influence food intake directly. Most of these cause meals to terminate and hence are called satiety signals…”

Satiety signals create a sensation of fullness and reduce your desire to eat.

These days, scientists are busy developing drugs to enhance satiety, so that people will eat less and lose weight. Increasing satiety while eating lower-Calories foods helps you lose weight by making it easier for you to consume less energy.

To achieve satiety (long-term absence of hunger) between meals, it’s useful to reach satiation (a feeling of repleteness) at each meal. But never go beyond “satiation” to “overfull”!

It’s just as important to avoid undereating as overeating. If you leave the dinner-table feeling slightly peckish and dissatisfied, you’re more likely to experience real hunger sooner after the meal. And then you’ll be tempted to reach for the nearest snack…

There are many benefits of reaching satiation at each meal.

• You will feel better than before you started the meal.

• You will feel satisfied.

• You can stop thinking about food for a while.

• You’re more likely to experience satiety between meals. Your appetite will take longer to be aroused.

• There is less chance that you’ll respond readily to appetite triggers in your environment.

• You’re less likely to get the urge to graze on snacks between meals.

• You’re less likely to want to consume a lot of food at your next meal.

• There’s less chance of your developing ‘cravings’.

An important key to losing weight is controlling how much energy you consume. This can be regulated by allowing your body to achieve satiation and satiety in a healthy way, without gorging on energy-dense foods.

Appetite.

Appetite is the desire to consume food. It may or may not be driven by hunger.

Eating triggers.

Certain things trigger physiological signals that tell your body to get ready for eating. These triggers may be psychological, chemical, cultural, the result of habit etc. Factors such as the smell or sight of food, sounds associated with food such as clinking tableware, and even mental images and thoughts of food stimulate your cerebral cortex. Your brain then sends messages via the vagus nerve to your stomach, telling it to secrete gastric juices in readiness for receiving food.

People usually call the sensation of desiring or needing food “hunger”, but that feeling may not be true hunger at all. The desire for food—which is called “appetite”—can be triggered by many things other than true hunger. Often, the terms “hunger” and “appetite” are used interchangeably, but their meanings are, in fact, different.

Regulation of hunger and appetite.

Your body regulates appetite via the neuroendocrine system. 

Together the endocrine system and nervous system can be called the “neuroendocrine system”. It’s the endocrine system that detects changes in your body, such as those that happen when food enters your mouth. It reacts to these changes by releasing hormonal messengers.

These appetite-regulating hormones include leptin, ghrelin, insulin and cholecystokinin (CCK). They play a role in hunger, satiation/ satiety and energy balance. Meanwhile your nervous system sends out electrical impulses and biochemicals called neurotransmitters. These direct the various parts of your digestive system to churn and process the food, and keep pushing it through your body. In other words when you eat food, your body responds in numerous ways. Signals are transmitted back and forth between your brain and your body’s other organs.

The stretching of the stomach signals fullness.

Your brain and stomach start to register feelings of fullness about 20 minutes after you begin eating a meal.

When you eat, food passes into the bag-like stomach, which stretches to accommodate the food. The stretching of your stomach triggers the appetite control switch in your brain. This tells you to stop eating (satiation) and dampens your hunger for a while, until your body requires more energy and nutrients.

TIP: To make good use of this appetite-reducing trigger, eat foods that occupy a lot of room in your stomach, but contain few Calories. Examples include vegetable soups, which contain quite a lot of water, and fresh garden salads.

When your stomach is chronically over-stretched by overeating, your body’s sensors lose their sensitivity. That appetite control switch in your brain becomes confused and the “stop eating” signals don’t work properly.

TIP: The solution to this problem—eat smaller portions.

CCK helps reduce appetite.

When food enters your stomach it also triggers off the release of cholecystokinin, or CCK. This is a protein that helps reduce appetite and prolong satiety. One of CCK’s actions is to close the valve that leads from your stomach into the lower GI tract, temporarily trapping the food so that the stomach can do its work of grinding and breaking down the food into smaller particles. The longer food remains in your stomach, the longer you feel full and satisfied.

Learn how to communicate with your body.

Work with your Inner Guardian, not against it.

For most healthy people, their Inner Guardian’s drive to ensure their survival is an overwhelming imperative. Your Inner Guardian exists solely for the purpose of preserving you (as long as you’re useful to your human tribe). It drives you to seek energy to consume, and it does its best to hang on to your existing stores of energy (body fat).

Many dieters who want to lose weight try to directly oppose and defeat these imperatives. This is a losing battle. Denying hunger usually leads to cravings and bingeing, and the vicious cycle begins again.

Your Inner Guardian is stuck in the past. It is hard-wired to help you survive in an ancient environment that has long since vanished; an environment that existed before the technological revolutions that made food so easy to come by. For millennia, this adaption has served humanity well. Now it’s having the opposite effect. In the 21st century many of us are surrounded by too much food, too easily acquired, containing too much energy.

When you try to fight against your Inner Guardian’s energy-seeking drives, you are likely to either:

• Lose the battle and gain weight

• Yo-yo diet, gaining and losing weight on the carousel of dieting

• Develop an eating disorder such as anorexia nervosa and/or bulimia, in which you battling obsessively and constantly to stay thin

• Die of starvation

So . . . what’s the answer?

You cannot re-wire your Inner Guardian, but fortunately you can communicate with it, if you learn to speak its ancient, silent language, “body-speech”.

By talking to it in its own language you can make it “know” that you are surrounded by ample food containing ample energy. And when it understands that, it can cease driving you with hunger and cravings to eat more, more, more, and pile on more and more weight.

Your Inner Guardian

You can actually use your Inner Guardian’s motivations to your advantage, if you recognize them and work with them.

If instead of fighting against your Inner Guardian you work with it, cooperating with it, you’re more likely to achieve your goal of weight loss. After all, your Guardian really does want what’s best for you.

These are the messages you need to send to your Inner Guardian:

• There is no danger of famine, so it’s okay for the Guardian to loosen its hold on your fat stores.

• Your body needs to utilize fat stores for activity, so your Guardian should free up that energy by burning the fat.

To find out more, listen to this episode. 

Body speech

Healthy young children are tuned in to their bodies. They know when they are really hungry, they know which foods will fulfil their nutritional needs, and they know when they’ve had enough to eat.

They understood their own body-speech.

You’re born with an innate ability to understand body-speech, but external influences can make you lose your sensitivity to it. Why do so many of us lose touch with this important, innate knowledge as we grow up? There could be several reasons, such as: 

• Your parents/caregivers might have believed it was their responsibility to cram as much food into you as possible, possibly resorting to cajoling, bribery or even punishment.

• You may not have been offered a wide range of fresh, nutrient dense foods to choose from.

• You might have been taught that sweet foods such as candy and desserts are “treats” or “rewards”, which makes Calorie dense, fatty, sugary foods seem more desirable.

• You were probably subjected to a barrage of junk food advertising on billboards, radio and TV.

• You were probably exposed to the brightly colored, alluring pictures on the wrappers of junk foods.

• You might have learned to eat when you’re not hungry, because it’s officially “meal-time” or because it’s a habit.

• You might have started eating “junk” food because of peer pressure.

• Dieting can interfere with your body-speech feedback mechanisms.

All of these messages, and more, can subvert your body’s natural instincts. By the time you became an adult you may have completely

lost touch with them, and forgotten how to listen to your body.

Getting back in touch with your body-speech

To counteract this:

• Become aware of your own natural biorhythms, your “body-clock”.

• Become aware of what makes you want food—your blood sugar levels, your emotions, seeing or smelling food, your food habits, whether you eat according to your appetite’s demands, or according to triggers of time and place.

• Don’t eat when you don’t really want to eat, just because it’s breakfast time or lunchtime or dinnertime, or someone offers food.

• Don’t allow your real hunger to become desperate ravenousness. Always have next meal planned and ready to be accessed quickly and easily. Keep emergency "100+" snacks on hand.

• Be aware of all the food you eat. Concentrate on it and make eating a special occasion. Never, for example, eat while walking around, reading or watching a movie!