How to lose weight on a plant-based diet

Most of us have grown up in a culture of fad dieting; think Atkins, Cabbage Soup, and support groups with the "biggest loser" being clapped in each week.

All these diets have one thing in common—they promote restriction. Restriction may well lead to a reduction in body weight, but it also leads to a lack of energy, irritability, and a shortfall of vital nutrients. Fad diets use the number on the scales as the most important a marker of success, above all other health markers such as blood pressure, cholesterol levels, energy levels, muscle mass, and even psychological wellbeing.

Restrictive diets are inherently unsustainable, leading to behaviour relapse and weight gain. The only result dieters are left with are feelings of failure, loss of confidence in healthy eating, and a disordered relationship with food. The key to success in weight management is finding a dietary pattern that you will enjoy, will leave you satisfied, and will promote long term and more gradual weight changes.

One meta-analysis found that vegetarian diets, and vegan diets in particular, appear to have a beneficial effect on weight reduction. Another study analysed the average weight of different populations with increasing amounts of animal products in their diet (from vegan to meat-eaters) and found that the only group that sat within a healthy weight range was the vegan group.

The proposed mechanisms in these studies result from consuming a "plant-based" diet, rather than simply the exclusion of animal foods that a "vegan" diet describes. Vegan convenience and "ultra-processed" foods such a sausage rolls and ice cream have become increasingly available; foods that are not considered beneficial to health or weight management. Whole plant foods are therefore the key to weight management when adopting a diet free from animal products.

An important concept in weight loss is that of the energy density of foods. Humans eat a similar weight of food at each day. If much of that food is energy-dense vegan convenience foods, then far more energy will be taken in, alongside sugar, salt and saturated fat. If much of that food is, instead, low energy-dense whole, plant foods, then we can eat more, fill our stomachs and feel satisfied, but we will have taken on much less energy, and much more fibre, water, polyphenols, and antioxidants that are beneficial for health and weight management.

Fibre, which comes exclusively from plant foods, is key to helping us to feel physically full as well as to feed our beneficial gut bacteria. Our gut bacteria play a crucial role in weight management as, when they break fibre down, they produce substances called short-chain fatty acids (SCFA). These SCFAs help regulate our hunger hormones (helping us to feel appropriately full), control our blood sugar levels, help us feel happier, and even support our immune system.

In addition, fibre reduces our risk for chronic diseases such as diabetes, heart disease, dementia and some types of cancer. Unfortunately, most of us lack fibre in our diet leaving us on a rollercoaster of hunger, cravings, low mood and susceptibility to illness and chronic disease.

If you are currently on, or moving to, a plant-based or vegan diet, aim to eat predominantly whole plant foods and cook from scratch as much as you can. Think of your diet as a big mix of fruits, vegetables, whole grains, beans, pulses, nuts, seeds, herbs and spices. 

An easy way to plan your diet is to imagine a circle representing your whole diet over the course of a day or week. Aim to cover half the plate with colourful fruits and vegetables like apples, berries, broccoli, bananas, beetroot, carrots, cauliflower, cucumber, and dark leafy greens like kale and spinach. Fill one quarter with healthy whole grains like brown rice, quinoa, wholewheat pasta, oats and wholemeal bread. Fill the final quarter with high protein plant foods such as beans, lentils, tofu and tempeh. Top your meal with a small amount of healthy fats such seeds or avocado. If weight reduction is your target, try to limit some of the higher energy dense plant foods such as nut butters and oil.

Eating this way will maximise the fibre and beneficial plant compounds, increase gut bacterial diversity, improve insulin sensitivity, reduce your energy intake without leaving you hungry, and support you to reach your best weight. Vegan convenience foods are of course fun to try, so you can enjoy these every now and again if you wish to. Remember it is what you consume most of the time that is important, not what you enjoy on special occasions.

After decades of faddy and restrictive diets, it’s time to take back our health, nourish our bodies, and enter a new realm of healthy and sustainable weight loss. But keep in mind, our weight does not indicate how healthy our body is. A healthy weight looks different on everyone and your best weight may be bigger or smaller than those around you. Aim for the healthiest diet that fits your lifestyle, move your body in ways you enjoy, develop healthy sleep habits, and spend time with loved ones, and your body will take care of the rest.

If you have any concerns over your body weight or related psychological health, it is always best to work with a registered professional to ensure you are making safe and effective changes.