The effects of fast food on your body and health

Regularly eating lots of fast food can have both short and long-term effects on your physical health, increase your risk of certain diseases and affect your mental wellbeing. Here we’ll take a look at some of the specific consequences fast food can have on your body. But first, what is fast food?

Fast food defined

Fast food refers to mass-produced, highly processed food that is prepared very quickly. This may include deep frying, grilling or microwaving pre-prepared ingredients, which are often precooked or frozen.

Common fast foods include burgers, fries, doughnuts, hot dogs, fried chicken, fish and chips, pizza, kebabs and submarine sandwiches (subs).

These are usually high in saturated fat, sugar, highly processed carbohydrates and calories. They are usually low in nutrients, vitamins, minerals and fibre.

How fast food affects your body

1. Your cardiovascular system

The high salt content in fast food increases the levels of sodium in your body, which raises your blood pressure. High blood pressure increases your risk of heart attack, heart disease, kidney disease, heart failure and stroke. 

Your risk of heart attack and stroke is also increased by high saturated fat levels in fast food as this can lead to high cholesterol and narrowed arteries (atherosclerosis). 

2. Your digestive system

High levels of salt and highly processed carbohydrates (eg in burger buns, breadcrumbs and pizza bases) in fast food can trigger bloating of your gut. Although bloating usually passes after 24 hours, it can leave you feeling quite uncomfortable.

The lack of fibre in fast food means that you may not be getting enough fibre to soften your stools. This can lead to constipation, causing you to strain when opening your bowels. This in turn increases your risk of haemorrhoids (piles) and developing a hernia. 

3. Your weight

Fast food is usually low in fibre. Fibre feeds good bacteria in your gut, which consequently helps you feel fuller for longer after a meal. Frequently eating fast food can therefore make it harder for you to control your appetite, causing you to eat more and put on excess weight. 

As fast food is also high in calories, eating more or larger portions of these foods can cause you to gain weight more quickly. 

Carrying excess weight puts a greater strain on your bones and joints, leading to joint pain and increasing your risk of osteoarthritis. 

4. Your risk of diabetes

Highly processed carbohydrates commonly found in fast foods have a high glycaemic index — this means they’re rapidly converted into sugar. Combined with the already high levels of sugar found in fast food, your body will experience sudden spikes in your blood sugar levels after a fast food meal. This triggers your pancreas to produce more of the hormone insulin to lower your blood sugar levels. 

Over time, these repeated spikes in blood sugar levels can make your body less responsive to insulin. Your pancreas, in response, makes more insulin and eventually its insulin-producing cells wear out, resulting in type 2 diabetes. 

Type 2 diabetes can damage multiple organs and systems in your body, including your eyes, kidneys and nerves, as well as increasing your risk of high blood pressure, atherosclerosis, heart disease and stroke.

5. Your mood

Rapid spikes and crashes in your blood sugar levels caused by the high amounts of sugar and highly processed carbohydrates in fast food can leave you feeling tired and consequently irritable. 

The lack of vitamins, minerals and nutrients in fast food can also lower your mood. 

6. Your skin

High salt levels in fast food can dehydrate your skin, leaving it dry and itchy, while high saturated fat levels can affect your hormones increasing your risk of acne. 

High sugar levels also have damaging effects on your skin. This is because sugar negatively alters the structure of collagen, a protein that helps your skin stay elastic. When your collagen is damaged, your skin appears more aged. 

How a healthy diet can help

You can avoid the effects of fast food by making sure it’s an occasional treat, not a regular meal choice. Instead, follow a healthy balanced diet rich in fresh vegetables and fruits, lean protein, whole grains and fibre. Also, pay attention to the size of your meal portions and try to swap out highly processed items for fresher alternatives eg swap sausages or ham for grilled chicken. 

This will ensure your body gets the nutrients, vitamins and minerals it needs to thrive, which will help improve your mood and reduce your risk of long-term diseases, such as diabetes and heart disease. 

Meals low in highly processed carbohydrates and rich in whole grains and fibre will also deliver a steady, sustained release of energy and help you stay fuller for longer so it’s easier to keep off excess weight. 

If you do occasionally indulge in a fast food meal, major outlets (those with more than 250 employees) are now legally required to display the calorie information of non-prepacked food and drinks in the UK. You can, therefore, check how many calories your meal includes to make a more informed choice.