How do I know if I'm really hungry?

The physical sensation of hunger involves a gnawing feeling in the stomach, weakness and sometimes headache. It’s distracting and uncomfortable. The overall effect, as we all know, is a powerful drive to eat.

The mechanisms in the body that produce this feeling of hunger are complicated and there are many theories that have been proposed in the past as to how food intake is controlled both in the short and longer term.

These include:

The Glucostatic Theory which suggested that food consumption is triggered by a decrease in blood glucose

The Lipostatic Theory which stated that body fat was the key in regulating eating behaviour

The Aminostatic Theory which suggested that amino acids (proteins) in the blood were crucial in determining satiety

The Hepatostatic Theory which focused on the metabolic activity of the liver

The Ischymetric Theory which held that brain receptors were sensitive to the turnover of all sources of energy (proteins, fats and carbohydrates)

The Thermostatic Theory which suggested that the heat generated during digestion inhibited further eating.

What the various theories shared was the common idea that energy intake was regulated by some feedback mechanism based on energy needs.

Recent advances in neuroscience, however, have led to a better understanding of the neurotransmitters (substances that pass signals in the brain), hormones and brain peptides involved in appetite and satiety.

Eating produces an increased blood glucose concentration, increased production of hormones such as insulin and glucagon and the gastrointestinal hormones and activates stomach and duodenal receptors, stretch receptors and chemical receptors. All of these factors work together to promote a feeling of fullness and to prevent hunger.

Unfortunately, there are factors that can undermine these signals from your body to stop eating, such as:

1. Palatability of food

What we choose to eat and how much we eat is strongly influenced by how the food tastes. People aren’t generally tempted to munch through bowls and bowls of plain boiled rice, but they could be tempted to get through a whole tube of Pringles without any trouble (does ‘once you pop you just can’t stop’ sound familiar?).

Fortunately (or perhaps unfortunately in this case!), food is not just about nutrition. It offers readily available and affordable feelings of pleasure. This is why it can be so easy to go overboard, even when there is no real hunger involved.

2. Conditioned responses

Sometimes eating can simply be a habit. If you always eat breakfast at 8, lunch at 1 and dinner at 6 o’clock, you may have conditioned your body to want to eat at those particular times. So even if you have a huge lunch, you may go ahead and have a full dinner in the evening, although you are not particularly hungry. You are responding in this way simply because it is your normal routine.

The same is true for the types of foods you eat. For example, if you always have a packet of crisps with your sandwich at lunchtime, it may be extremely difficult to change this habit (and I don’t mean switching to a chocolate bar instead!), despite feeling full after eating the sandwich.

3. Stress

Many people experience stress as an almost normal part of their daily life yet few of us have the training to be able to cope with the ups and downs that life throws at us. Some of us turn to counselors for help, some of us shop-till-we-drop, some turn to drugs or alcohol to escape and many of us use food. This is partly related to the feel-good-factor that food can readily provide, but there may also be trigger foods because of their associations.

For example, if you were given chocolate as a reward when you were a child this may be what you crave when times are tough. Equally, if you have ‘forbidden’ foods, you may use them to rebel against a situation you feel you cannot control. There may be other foods you find particularly soothing, due to their flavour and texture. Ice cream is a good example.

If you do turn to food in times of stress, the only way to combat this is to recognise what you are doing. Identify the source of stress and then address it, rather than burying it under a mountain of chocolate or chips.

A good way to do this is to keep a diary of your food intake and your feelings of stress. You will begin to see a pattern emerging. The same is true for the timing of your food intake and the types of food you are craving.

Really think about what you are eating, when you are eating and more importantly why you are eating. It will become very clear to you when you are truly hungry and when you are not.

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