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Healthy eating: Why teens gorge and older people peck – DW (English)

health-and-well-being

Our body tells us more or less what to eat and when to eat, and maybe we should listen, said Susanne Klaus, a chief researcher at the German Institution of Human Nutrition.

That makes sense. But the way our body demands energy of us isn’t the same throughout our lifetimes. From being spoon-fed by parents when we’re infants to sneaking sugary sweets when we’re children, to eating everything in sight as teenagers and then pecking on small, simple plates in later stages of life, our appetites change as the years roll on. Understanding why can help ensure good health in our later years.

The hunger hormones and how they work

Eating food is a functional necessity: Without the energy we draw from it, we simply wouldn’t survive. Carbohydrates in our food are converted into energy while fats and amino acids help create the vital proteins and other structures that help the body function.

To ensure these processes run like clockwork, our bodies employ a complex system of chemical drivers that prompt us to seek (or stop seeking) food. These are sometimes called hunger hormones. Aside from leptin, ghrelin is perhaps the best-known hunger hormone. Released into the bloodstream by the stomach, ghrelin tells the brain to get us eating. When you’re full, ghrelin release slows, giving a sensation of fullness.

Other hormones regulate feelings of fullness and emptiness, too. These include insulin and other pancreatic hormones like GLP-1, which the diabetes drug, Ozempic, mimics.

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The mechanics of digestion

When hunger hormones prompt you to stick food in your mouth, the body uses digestive processes to quite literally eat away at your meal. Mechanical digestion begins in your mouth, where you grind your food into smaller, mushier forms you can swallow. This process continues as this swallowed slurry is forced down the esophagus into your stomach—a process known as peristalsis.

Alongside this process is chemical digestion. This begins in the mouth with amylase enzymes in saliva breaking down starches in food. More of these digestive enzymes are in the stomach to finish the job so water and nutrients can then be absorbed from the intestines into the bloodstream.

How your appetite changes as you age

The impulse for food hits overdrive when you reach adolescence, with the body craving energy to fuel its most important growth stage—puberty—spurring it toward physical and sexual maturity.

But lifelong nutrition can be a challenge. For older people, there is a risk of the body becoming less effective at prompting the necessary intake of nutrients. Some studies have shown changes to hunger hormone secretion patterns in later life.

“When people age, on average, they lose muscle mass and muscle is the compartment which uses the most energy,” said Klaus.

A major driver of muscle mass reduction is a failure to consume sufficient protein. Daniel Crabtree, a late-life stage nutrition researcher at the University of Aberdeen, explained that older people’s protein intake does tend to be below what’s recommended, and that can include physiological factors and other signs of an ageing body—from problems with your teeth to changes in taste or smell.

Edited by: Zulfikar Abbany