Our diets are made up of a mixture of different nutrients that can impact our health in various ways. Nutrition studies that only look at one thing at a time, like comparing high-fat to low-fat diets, often miss out on how these nutrients interact with each other and affect our metabolism. This can lead to confusing and conflicting conclusions about how nutrients influence diseases like diabetes or obesity. To truly understand what diet is best for our health, we need to consider how nutrients work together. A nutrition science methodology called nutritional geometry (NG) helps with this. It's a tool that shows how different nutrients (proteins, fats, carbohydrates) in our food can affect things like our body weight, our appetite, our blood glucose and cholesterol levels. This approach has been used successfully in various animals, from flies to humans, to figure out how different diets affect markers of health and lifespan.

In recent years, scientists have been using the NG approach to study the diets of children and adults. For example, in Australian children, they found that having less protein compared to fat and carbs in the diet was linked to starting puberty earlier. In Finnish children, the amount of energy they got from protein affected how many calories they ate in a day. So, it's not just about how much of each nutrient we eat, but also about how they work together. In this project, we aim to use the NG methodology to study how diets with different ratios of protein, fat and carbohydrate influence their health status and risk of obesity and diabetes across different stages of childhood.

When it comes to carbohydrates, the quality matters too, not just the quantity. Carbs are the major source of energy for the majority of population, but not all carbs are the same. The glycemic index (GI) is a way to measure how quickly a food makes our blood sugar rise and glycemic load (GL) is a measure of how much the food will raise a person's blood glucose level after eating it. In this project, we will generate evidence for the relationship between GI and GL of the diet in childhood and its link with growth, development, obesity and various markers of health. In addition, sugary drinks with fructose can be bad for our health, even if they have a lower GI compared to other sugars. This is because fructose can make our liver create more fat, leading to weight gain and other issues. So, it's not just about the type of carbs we eat, but how they affect our bodies in different ways. Therefore, we will assess how the level of fructose in the diet predisposes a child to the risk of obesity and diabetes.