What is a healthy diet?

What is a healthy diet?

A healthy diet is one that optimises health by providing all essential nutrition while also maintaining an appropriate weight.

The composition of such a diet is subject to vigorous debate both amongst experts and lay people.

Even in the 21stcentury, folklore and conventional wisdom continue to shape mainstream nutritional beliefs in the absence of convincing evidence. This is in part due to the difficulties and expense of performing suitable interventional research, with nutrition science historically based on less robust epidemiological research. Findings from these observational studies are often demonstrated to be erroneous when tested in randomised controlled trials.

In recent years there has been growing interest in nutritional research thanks to increased funding and improved research methodologies. Combined with advancements in molecular biology and biochemistry, this has resulted in an improved understanding of healthy diets and underlying physiological mechanisms. These new understandings however, often contrast with existing orthodoxy and are not universally accepted.

Optimal dietary macronutrient composition is perhaps the most contentious topic. Sugar has received much attention, many arguing it has increased potential for causing metabolic harms compared to other carbohydrates. The importance of sodium restriction, benefits of dietary fibre and required water intake are other longstanding beliefs that are increasingly questioned. The gut microbiome is an exciting new area of nutritional science, however many claims regarding pre- and probiotics are being made in advance of definitive evidence.


A significant amount of conventional thinking about nutrition is not well supported by evidence. Continue reading the resources pages to examine the evidence base for current nutritional recommendations, exploring the current understanding of macronutrients, micronutrients, fluids and different dietary patterns.