Sugar

Sugar is found in all foods that contain carbohydrates, including fruit, grains, dairy and vegetables – even bitter green veggies like broccoli contain some. When doctors fret about sugar, though, they’re seldom talking about the kind naturally occurring in these foods. Instead they are worried about “added sugar”, which refers to any calorie-containing sweeteners added to food during preparation, whether in your kitchen or on the food production line.

There are many types of sugar, each with their own level of sweetness and calorie content. All carbohydrates are made up from three simple sugars known as monosaccharides: glucose, fructose and galactose. The group together in different combinations to make more complex carbohydrates. Table sugar or sucrose is made up of fructose and glucose, for instance. Milk sugar, lactose, is made up of glucose and galactose.

Natural sweeteners such as honey or agave syrup often taste sweeter than table sugar, but can also have more calories per teaspoon. Ultimately, to people who study nutrition, it all more or less balances out. Sugar is sugar.

People who eat more added sugar tend to put on weight, and those who cut back on it tend to lose weight. There are a few possible explanations for this. Most simply, people who eat more sugar tend to eat more, full stop.

But how you consume sugar also makes a difference. Drinking a sugar-sweetened beverage gives you an influx of calories without making you feel full – so-called “empty calories”. Eating an orange, with the accompanying fibre, makes you feel much fuller than drinking a glass of orange juice – even though the juice may have four to five times as many calories.

Having more added sugar in your diet is associated with an increased risk of obesity and heart disease. That’s because sugar can contribute to higher blood pressure and raise the risk for chronic inflammation, both processes that increase the risk of heart disease. High amounts of sugar can also stress the liver, because our bodies metabolise the fructose in sugar much in the way we process alcohol, converting any excess to fat. Having too much of this type of fat is associated with increased risk for insulin resistance, a precursor to type 2 diabetes.

Glucose, meanwhile, can be taken up by all of the cells in the body with the help of the hormone insulin, produced by the pancreas. The more glucose you consume, the more insulin your pancreas has to produce. And if you are consuming more than your body needs as fuel, the insulin will shunt the rest into your fat cells. Being overweight and having a high-sugar diet are also known risk factors for insulin resistance. Tiffany O’Callaghan