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What is healthy eating?

Updated: Jan 18


Written by Dr Charlotte Verney MBCHB BSc MRCGP MRCEM Dip IBLM/BSLM

GP with specialist interest in Lifestyle Medicine at One5 Health


We all know that ‘healthy eating’ is good for you, but what does healthy eating look like? What difference could it make to you, both now and in the future? We have produced this article to summarise the key concepts of evidence based healthy eating, one of the six pillars of lifestyle medicine.


Globally it is estimated that 11 million deaths occur annually due to unhealthy eating (1). Many more individuals are affected by chronic disease, such as diabetes and heart disease, which may have been preventable with the optimum nutrition. The evidence is compelling and increasingly this is being recognised within Western Medicine where the focus has historically been reactive rather than proactive. Adopting a healthy relationship with food is one of the key areas which can positively impact your health and prevent disease.

There is no single dietary approach advocated, instead evidence based nutrition promotes a whole food, predominantly plant based and minimally processed diet. This is achievable whether you choose a mixed, vegetarian, vegan, lower carbohydrate or mediterranean diet.

Specifically, we will explore each of the following concepts:

1. What do we mean by whole foods?

2. What is the issue with processing?

3. Why should most of our diet come from plants?

4. What does this look like day to day?

5. What’s in it for me?

What do we mean by whole foods?

Whole foods are typically single ingredient foods, i.e. they have not been processed in any way or only minimally processed. Examples of whole foods include vegetables, fruits, nuts, seeds, meat, fish, whole grains and legumes. Simply put, the more whole (and less processed) a food is, the more nutritious that food is.

Whole grains are made up of three parts: a nutritious outer layer known as bran, the seed’s nutrient-rich embryo called germ and the endosperm which is the germ’s starchy food supply. Whole grains are grains which are still intact and have all three parts, in comparison to grains which have been through a milling process and are often referred to as ‘refined’, eg white flour. Ironically, refined grains are less nutritious than their whole grain predecessors which contain more iron, vitamins, minerals and soluble fibre. A diet rich in whole grains can reduce the risk of heart disease (2). Examples of whole grains include oats, whole wheat, whole grain rye, quinoa and brown rice. When shopping for flour the key is to look for the word ‘whole’ which suggests the whole grain has been used.

Healthy eating advice often mentions consumption of legumes, but what exactly do we mean by legumes and are they the same as pulses and beans? Legumes are intact plants from the third largest flowering plant family (Fabaceae) including leaves, stems and pods. A pulse is the edible seed part of a legume plant and includes lentils, peas and beans. Beans, therefore, are just one type of pulse, and examples include chickpeas, kidney, black, pinto beans.

The type of whole food will determine the amount of beneficial nutrients including vitamins, minerals such as magnesium, protein, iron, antioxidants and fibre, which is why choosing whole foods is one part of the key to a healthy diet.


What is the issue with processing?

Cooking, seasoning, preserving and combining foods all alter whole foods from their raw form and therefore technically are types of processing. Taking this into account it is not the case that all processing of foods is bad. Rather it is ‘ultra processed’ foods (a concept introduced by Carlos Monteiro (8)) that we need to be cautious of. Ultra processed foods involve any of: fractioning whole foods into substances, cosmetic additives, chemical modifications or sophisticated packaging. These processes afford some advantages (including shelf life, convenience, palatability and low cost), however they come with the crucial downside of adversely affecting our health. The problem is these foods are created by the addition of substances which are never or very rarely used in the kitchen and the further we get from the raw whole food, the less nutritious it becomes.

In general, foods which are minimally processed can be eaten relatively freely, while those which have been substantially altered should be eaten very sparingly. The reality in the UK is that just over 50% of food purchased by UK households is ultra processed (9). The food industry uses marketing to its advantage and often food is labelled in such a way to suggest it is a healthy choice when this isn’t always the case.

A simple way to identify foods which are ultra processed are those where it is difficult to visualise everything that has happened to that food before it is consumed. For example, it is easy to visualise an apple being picked, cleaned and transported to the supermarket (unprocessed), relatively easy to visualise it becoming apple sauce (minimally processed), but less easy to visualise how it became a packaged apple fritter (ultra processed).

A healthy diet involves aiming to eat foods as close to their whole food, natural form, minimising the amount of processing that has been involved. For example eating whole rolled oats is preferable to eating quick oats, or making your own roasted vegetable and tomato pasta sauce is preferable to using a jar of sauce.

Why should most of our diet come from plants?

There is good evidence for adopting a predominantly plant based diet, which means eating a diet consisting mainly of fruits, vegetables, whole grains, legumes, nuts and seeds and in doing so consuming meat and dairy products more sparingly. A plant based diet has been shown to significantly reduce the incidence of heart disease (3), type 2 diabetes, cancer (4) and all-cause mortality. It is not only a dietary approach to prevent ill health, but can and should also be used in the treatment of many chronic diseases, including type 2 diabetes and obesity.

Plants are full of fibre, high in vitamins and minerals, do not contain any cholesterol and are low in saturated fat. Plant foods are typically more nutritious than animal foods, for example a portion of blackberries provides 100 times as many antioxidants as an egg.

One of the traditional concerns with a plant based diet is not getting enough of certain essential nutrients, for example protein, calcium, iron and vitamin B12. However, ensuring you incorporate the right plant based foods in your diet, you can easily achieve all of the macronutrients (carbohydrates, protein, fat, fibre) and micronutrients (vitamins and minerals) that you need. Take protein for example, there are multiple plant based sources of protein including chickpeas, lentils, quinoa, broccoli, black beans, peanut butter and tofu to name a few. In fact your protein requirement can easily be met in plants alone, avoiding the downsides t