What is a plant-based diet?

How does a plant-based diet work?

There are various interpretations of what ‘plant-based’ eating looks like. Some people choose to include small amounts of animal products such as meat and fish while focusing mainly on plant foods – this is often referred to as a semi-vegetarian or flexitarian diet. Plans that cut out meat but still include fish are known as pescatarian diets. Those who don’t eat meat or fish but still include dairy and eggs are vegetarian, while those who cut out all animal-derived products, including dairy, eggs, honey and gelatine, are referred to as vegan.

How do you follow a plant-based diet?

People following plant-based diets consume a wide variety of fruits, vegetables and pulses. This means they are likely to find it easier to meet their five-a-day target. They also tend to enjoy good intakes of fibre, vitamins and minerals, including folate, vitamin C and potassium, all of which are important for good health.

What can I eat on a plant-based diet?

People adopting this style of eating emphasise whole, plant-based, minimally processed foods, including:

• Plant proteins such as beans and pulses like soya, tofu, tempeh and lentils
• Nuts, seeds and other healthy fats including olive oil
• Fruits and vegetables
• Wholegrains and pseudo cereals such as quinoa, buckwheat and teff

What food should I avoid on a plant-based diet?

While plant-based eating encourages you to minimise or avoid foods sourced from animals, such as meat and fish, it doesn’t seek to ban foods. Instead it tries to encourage plant foods over others.

It's also worth noting that ‘plant-based’ doesn’t automatically mean 'healthy', particularly when it comes to processed and packaged foods. Technically, products such as refined sugar, white flour and certain vegetable fats can all be labelled plant-based, but this doesn’t mean they should make up the bulk of your diet.

Read more about vegan meat alternatives.

Will I lose weight following a plant-based diet?

Those who follow a vegan, vegetarian or semi-vegetarian diet typically have a lower body mass index (BMI) compared to those who adopt an omnivorous one. This was highlighted by one study, which reported that a group of postmenopausal women who followed a semi-vegetarian diet for 20 years had significantly lower body weight, BMI and body fat than their non-vegetarian equivalents.

In addition to the obvious dietary differences that may account for weight loss – a vegetarian diet being higher in fibre, and lower in fat and calories – there may be an element of restrained eating which contributes as well. Therefore, until further research is conducted, it's difficult to say whether adopting a plant-based diet is a surefire strategy for sustained weight loss.

Are plant-based diets healthy? A nutritionist’s view…

Plant-based diets, including vegan diets, may be healthy as long as they are balanced and nutritionally adequate. When followed consistently, a well-balanced, plant-based diet that focuses on wholegrains, fruit, vegetables, legumes, nuts and seeds may provide health benefits. These include a lower BMI, lower cholesterol levels and a reduced incidence of chronic diseases including type 2 diabetes, heart disease as well as potential protection from certain cancers including prostate and breast cancer.

Like any diet, the health benefits achieved are dependent on the quality and nutritional adequacy of the diet – this means replacing refined, typically ‘white’ carbohydrates with wholegrains, avoiding sugary and highly processed foods, and focusing on good quality plant-based protein and fats including nuts, seeds, legumes and pulses.

When following a plant-based diet, there are some nutrients that you may need to focus on. These include protein, vitamin B12, the vitamins and minerals needed for bone health, including calcium and vitamin D, and the essential omega-3 fatty acids. These nutrients are not found easily in plant foods, so you may need to source them from fortified foods such as plant milks, spreads and cereals.

If you are considering taking a supplement to support your nutritional intake, discuss this with your GP first.

Should I follow a plant-based diet?

Those following a plant-based diet may need to plan their meals a little more carefully. Arming yourself with some dietary information can make all the difference. You might find it useful to read our guides on vegetarian sources of protein, vitamin B12 as well as the best sources of omega-3 fatty acids.

If you are significantly changing your diet, it may be useful to start slowly – perhaps introducing two or three plant-based meals, or days, a week. This allows your body to adapt to new foods and higher levels of certain nutrients, such as fibre. It also allows you to experiment with new foods and build up a storecupboard of additional staples.

Like this? Read more health guides...

Why eat 30 plant foods a week?
10 healthy plant-based meals
What is the planetary health diet?
How to eat a balanced diet for vegetarians
How to switch to a vegan diet

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This article was published on 29 December 2023 by Kerry Torrens.

Kerry Torrens is a qualified Nutritionist (MBANT) with a postgraduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Applied Nutrition and Nutritional Therapy (BANT) and a member of the Guild of Food Writers. Over the last two decades she has been a contributing author to a number of nutritional and cookery publications including Good Food

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