Hunger, appetite and cravings…

• Hunger is described as the demand for calories
• Appetite is described as the demand for particular food/s
• Cravings occur when you eat but you are not hungry, it is more of a rewarding want rather than a need to eat.

Hunger represents a physiological need to eat. It is controlled by neurological and hormonal signals and arises only after a few hours without food.

The hypothalamus processes these signals in relation to nutrient and energy availability.

Hunger and satiety are sensations. Satiety in the absence of hunger is the sensation of feeling full which occurs (5-20 minutes) shortly after eating.

Appetite is another sensation experienced when eating and is said to be the desire to eat food.

The release of the endocrine hormone ghrelin sends signals to the hypothalamus via blood circulation. This is absorbed into the stomach via afferent signals when it is empty.

When food is consumed, the absorption stops and signals are sent to the hypothalamus in the brain to ‘register’ consumption of food.

Ghrelin is an acute hormone that follows meal patterns. It is the body’s natural appetite hormone and as ghrelin builds between meals, so too does appetite. Ghrelin levels are lowest approximately 30 minutes before a meal.

Leptin on the other hand is a hormone secreted from the adipocyte and acts to control hunger. Signals are sent to the brain once food is consumed to suppress hunger and identify satiation.

This reduces the motivation to eat.

Leptin levels drop significantly after hours of non-consumption. The lower levels of leptin cause the release of ghrelin, which in turn reinitiates the feeling of hunger. The fluctuation of leptin and ghrelin levels result in the motivation of an organism to consume food.

The increase in ghrelin may enhance appetite/cravings evoked by the sight of food, while an increase in stress can also influence the hormones’ production.

This may explain why or how we feel hungry in stressful situations mediated by the environment, behaviour and/or other cognitive stimuli.

Factors affecting food choices…

Other than the neurological determinants of food choice that affect hunger, appetite, satiety and cravings, have you ever considered the environmental and behavioural effects that supplement and lead to these choices?

Our environments can effect our emotions. This plays a big part in the behaviours we display.

If you are at home or in a comfortable environment feeling stressed or anxious due to a bereavement for example, it could lead to emotional overindulgence in high fat/sugar foods. Comfort eating at its finest!

This is largely due to your emotional state, the availability of such foods in your environment and the factors that lead you to purchase the foods in the first place.

Palatability also determines food choice. We eat what we enjoy, including both healthy and unhealthy foods. The environment affects our choices. Our psychological choices are lead by the environments we are in (home, school, work, gym) – also a choice.

Choices determine our food preference, which can be regulated by cultural factors and palatability.

The first thing you need to do is understand how the environments you are in can influence the decisions you make with food intake. In scientific terms, we need to manage our cognitive and biological controls to achieve balance and weight homeostasis.