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What is healthy eating?

January 18, 2023

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 to animal proteins, which include higher levels of saturated fats, trans fats, higher levels of certain amino acids associated with kidney disease and cancer and lower levels of micronutrients as discussed above (5).

Considering calcium, while dairy foods are an undeniably good source, the calcium is then packaged with saturated fats. In contrast, calcium rich plant foods including kale, cabbage, broccoli, dried figs, sesame, chia, poppy seeds, milk alternatives such as almond milk and fortified juices contain no saturated fats.

Similarly iron is typically thought of as being found in red meat, yet lentils, chickpeas, beans, cashew nuts, chia seeds, ground linseed, pumpkin seeds, kale and dried fruit are all iron-rich. You have probably started to see that many of the plant based foods are repeatedly mentioned as good sources of lots of nutrients. Vitamin B12 is not found in plant based foods and therefore if you choose not to consume any animal products (the main sources of vitamin B12) it is possible to meet this nutritional requirement by eating vitamin B12 fortified foods such as cereals, plant milks or nutritional yeast or by taking a daily supplement.

Interestingly, eating a western diet we typically eat an adequate amount of protein. However, in contrast, less than 5% of American’s meet the recommended daily minimum intake of fibre (6). Compared to animal products which contain no fibre, plant based foods provide your body with essential fibre it needs to function well. There are two types of fibre, both of which are good for us and serve slightly different functions. Soluble fibre, found in oats, beans, lentils, flaxseed and some vegetables, helps to mop up ‘bad’ cholesterol or low density lipoproteins (LDLs). Insoluble fibre is not digested, but instead moves into the large gut (colon) where it helps to feed the good bacteria, essential to maintaining a healthy microbiome.

Another benefit to eating a plant based diet is maintaining a healthy weight. In England 75% of the adult population aged between 45 and 74 years are overweight or obese (7), highlighting the challenge of weight management when consuming a typical western diet. Michael Pollan, New York Times bestselling writer, famously summarised three rules to a healthy diet: “eat food, not too much, mostly plants”. As well as the health benefits of plants summarised above, plants help us to feel full, based on calorie density. In a nutshell, while one calorie of oil is the same as one calorie of berries biochemically, they have a totally different volume. The volume is important, as foods with low calorie density (i.e. low calorie to volume ratio) such as berries, or broccoli, trigger the “I’m full” signal in our stomachs, also called satiety (6). This is why a dietary approach to maintaining a healthy weight isn’t as simple as reducing portion size and eating less, as this can often leave you feeling unsatisfied and hungry. In fact, much better to eat more of the right plant based, low calorie dense foods, that leave you feeling satiated. The best predictive factor of how well a food makes you feel satisfied, is its water content, not its carbohydrate, fat or protein content. When ranking the water content of foods, plants have the highest with 70-95% water (vegetables, then fruit, then whole grains and starchy vegetables), followed by animal products and lastly processed foods.

What does this look like day to day?

Eating home cooked food is the simplest and most cost effective way to achieve a whole food, predominantly plant based diet and minimally processed diet. In doing so you source your own ingredients and can easily see what you are eating. If you currently enjoy animal products on a daily basis and are keen to gain some of the health benefits seen with a diet rich in plant foods, an approach is to aim for your plate to be mainly plants, but not exclusively. For example, it’s better to eat a salad full of nutritious plants with a sprinkling of bacon lardons, or soft boiled egg, rather than not eat the salad at all.

It is also important to remember that your health will largely be impacted by the diet you adopt most of the time. For many people it is unrealistic to consider never eating another steak, or triple fried chips and in fact aiming to make healthy choices most of the time, is more likely to lead to a healthier diet overall.

The EAT Lancet Commission infographic below demonstrates this, highlighting that a healthy diet will consist mostly of plants, but for many not exclusively.

The table below provides another summary by looking at the three major macronutrients. What you’ll notice is that by remembering the key themes of choosing whole foods and predominantly plant based options you can’t go far wrong.

What’s in it for me?

As discussed throughout the article there is strong evidence that eating a healthy diet can reduce the risk of premature death. Making positive choices and eating healthily can also impact you now.

To get a deeper understanding of your how your diet and nutrition can impact your health book a Well Woman or Well Man check today for a holistic health check with a lifestyle and nutrition plan personalised to your results.


1. Lancet 2019 Global Burden of Disease Study

2. Steffen LM, Jacobs DR, Stevens J, Shahar E, Carithers T, Folsom AR. Associations of whole-grain, refined-grain, and fruit and vegetable consumption with risks of all-cause mortality and incident coronary artery disease and ischemic stroke: The atherosclerosis risk in communities (ARIC) study. The American Journal of Clinical Nutrition. 2003;78(3):383–90.

3. Kim H, Caulfield LE, Garcia‐Larsen V, Steffen LM, Coresh J, Rebholz CM. Plant‐based diets are associated with a lower risk of incident cardiovascular disease, cardiovascular disease mortality, and all‐cause mortality in a general population of middle‐aged adults. Journal of the American Heart Association. 2019;8(16).

4. Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Critical Reviews in Food Science and Nutrition. 2017;57(17):3640–9.

5. Budhathoki S, Sawada N, Iwasaki M, Yamaji T, Goto A, Kotemori A, et al. Association of Animal and plant protein intake with all-cause and cause-specific mortality in a Japanese cohort. JAMA Internal Medicine. 2019;179(11):1509.

6. Greger M. A whole food plant-based diet is effective for weight loss: The evidence. American Journal of Lifestyle Medicine. 2020;14(5):500–10.

7. Parliament UK. Obesity statistics - House of Commons Library [Internet]. Obesity Statistics. 2022 [cited 2022Dec5]. Available from: https://commonslibrary.parliament.uk/research-briefings/sn03336/

8. Monteiro CA, Cannon G, Levy RB, Moubarac J-C, Louzada MLC, Rauber F, et al. Ultra-processed foods: What they are and how to identify them. Public Health Nutrition. 2019;22(5):936–41.

9. BSLM. Eating a healthy diet and avoiding processed foods [Internet]. British Society of Lifestyle Medicine. 2022 [cited 2022Dec5]. Available from: https://bslm.org.uk/eating-a-healthy-diet-and-avoiding-processed-foods/

10. EAT-Lancet. The Planetary Health Diet [Internet]. EAT. 2021 [cited 2022Dec6]. Available from: https://eatforum.org/eat-lancet-commission/the-planetary-health-diet-and-you/

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