We put 10 of the most common nutrition questions to Prof Grant Schofield and Dr Caryn Zinn. Here’s question 3: What is a healthy diet?

A healthy diet is one that is low in human interference. In other words, it avoids the category of foods that we call ultra-processed foods. In most developed countries, more than half, possibly two-thirds, of what people put in their shopping trolleys at supermarkets, would be categorised as ultra-processed food.

That’s the target for getting people healthier-eating. You can do all the work about macronutrients and other components of nutrition, but it starts with this – a healthy diet is one which is less processed.

Moving with that philosophy of low-HI (human interference factor), a healthy diet, irrespective of what the macronutrients ratios are – carbohydrates, protein and fat – the micronutrients and fibre content need to be satisfied. So, if you can choose a range of whole, unprocessed foods – such as meat, fish, chicken, eggs, milk and dairy, nuts and seeds, and fruit and vegetables, in the proportions that give you all the micronutrients – vitamins, minerals, phytochemicals – and fibre you need, that is considered a healthy diet.

Here’s one more for you – a healthy diet should also allow you to keep a stable blood glucose and prevent your hyper-secreting insulin – that’s a more scientific answer. If your diet makes you get high glucose, for example, if you are insulin-resistant (if you have pre-diabetes or diabetes) and you consume a lot of fruit, such as bananas, apples and oranges, then you won’t be able to sustain that. So, it is context-dependent.