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  • Writer's pictureMelanie

Why not to diet...the latest diet trends, and how to achieve sustainable and healthy weight loss.

Updated: Jul 10, 2023

diet plan book on table with fork and bowl of salad

The New Year is traditionally packed with an invitation to try the latest diet to shift the pounds we may have added over the holiday season. I am not a huge fan of diet culture, having seen many people desperately try to stick to low-carb, low-fat, low-calorie diets, only to put on more weight afterwards, or for it to spiral downwards towards eating disorders. The body is designed to eat a range of foods to fuel it, which includes carbohydrates, fats and enough calories to provide for energy needs. Below, I look at the pitfalls of common diet trends and give an insight as to what can be more effective for sustainable and healthy weight loss.

Low-calorie diets:

Just being alive takes on average 1600 kcal a day, this is the basal metabolic rate (BMR), which is the number of calories needed to cover basic functions such as brain function, heart, lungs kidneys and liver. On top of this, there is an energy requirement for digestion and any movement, such as sitting up, filling the kettle etc., let alone actual exercise. Most low-calorie diets suggest eating 800-1200kcal a day, way below the BMR.

Insufficient energy intake has some pretty serious consequences:

1. It lowers metabolism. Low-calorie diets can decrease the amount of energy the body burns by up to 23%, as it goes into a famine survival mode, which lasts long after the diet has stopped. This goes some way to explaining why many people regain the weight they lose, and often increase their weight, as their set-point increases. Muscle mass is also lost which includes heart muscle. It is important to ensure your calorie intake is never below your BMR.

2. It can lead to nutrient deficiencies and fatigue. By reducing calories, you tend to reduce the actual amount you eat, which may mean not getting enough vitamins and minerals such as iron, folate and vitamin B12, which can lead to anaemia and fatigue.

Low-carbohydrate diets can also cause fatigue in some people. It is worth noting that the brain requires carbohydrates to function!

3. Restricting calories can also lead to deficiencies in protein, calcium, magnesium, and B vitamins, which can lead to muscle loss, and hair thinning. Reduced bone density, cramps, and heart rhythm irregularities.

4. Long-term calorie restriction can lead to reduced fertility.

5. Insufficient nutrition and energy intake can lead to reduced immunity, so increasing the risk of infections and illness.

As can be seen, it is important not to follow any really low-calorie diets, especially those that rely on processed foods rather than real foods due to a reduction in nutrients. Additionally, low-calorie diets are notoriously difficult to stick to due to their restrictive nature. (1)(2)

Low-fat diets:

While reducing fat intake can have health benefits, especially if you reduce the amount of saturated fats, scientific trials have concluded that low-fat diets are not helpful for long-term weight loss. It is far better to include healthy fats in your diet as they are needed for brain health, cell membrane structure, manufacture of hormones, and gut integrity. Healthy fats include olive oil, seeds and nuts. (1)

Keto diet:

The keto diet involves extremely low levels of carbohydrates, with increased levels of protein and fats. Although the keto approach can reduce appetite and can be useful in certain circumstances, there is a lack of evidence for its effectiveness and safety in the long term, and it is contraindicated in pregnant women, those with type-1 diabetes, those with kidney failure or cardiac arrhythmia. It is a diet that should only be used under supervision. (1)

Intermittent fasting:

There has been a lot of hype around intermittent fasting over the past few years. Common approaches are alternate-day fasting, 5:2 fasting, and time-restricted eating. There are some benefits seen from using these approaches such as reduced insulin resistance, improved immunity and improved cognition. However, this is not with eating a typical Western diet of processed foods with low fruit and vegetable intake, but with eating a well-balanced diet combined with intermittent fasting. There is little evidence to support the long-term use of this approach. (1)

So what can you do if you need to lose some weight?

A whole-food plant-based (WFPB) diet or Mediterranean diet is the best approach, they support weight loss and are beneficial to health in the long term.

Whole food plant-based (WFPB) diet

Evidence also shows that a well-planned whole food plant-based (WFPB) diet is a good long-term approach, although supplementation is needed to ensure sufficient quantities of omega 3, vitamin D and vitamin B12. A WFPB diet has been shown to achieve greater weight loss than other approaches. It has also been shown to reverse heart disease and to be helpful in preventing and reversing other chronic conditions such as type-2 diabetes and hypertension. It reduces the risk of many cancers, brain disease and supports gut health, immunity, and mental health. (3)(4)

What is a WFPB diet?

It is an approach that is based on eating unprocessed plant-based foods the majority of the time. This does mean cooking from scratch as processed foods such as crisps, ready meals, sausages or pot noodles are not beneficial to long-term health. (That is not to say you can never eat these things, just make them a rare exception rather than an everyday/weekly occurrence).

A WFPB diet includes 7-9 portions of vegetables and fruit a day (2-3 fruit, 5-6 vegetables). Nuts and seeds are eaten daily as are beans and legumes and wholegrains.

Dr Michael Gregor has produced his Daily Dozen list which is a helpful checklist of what to include in a WFPB diet:

Dr Michel Gregor's Daily Dozen chart


Most of the recipes on my website follow a WFPB approach. There are some excellent cookbooks available, look for ones that include plant and legume-based recipes, rather than ones relying on processed ingredients.

I recommend meal planning each week, and batch cooking where possible to ensure that you have things ready for when you can’t be bothered to cook, e.g. chilli, curry, lentil Bolognese, and bean burgers can all be frozen. Use leftovers for breakfasts and lunches, and batch-make salads and breakfasts to reduce the amount of time you spend cooking and preparing. Try to ensure you have a protein source in each meal, tofu, nuts, lentils or beans are a good place to start.

Mediterranean diet

For those not wanting to become plant-based, following a Mediterranean diet is thought to be the best approach as it includes an increase in consumption of fruit and vegetables, is high in fibre, and includes protein and healthy fats. This is an approach that can be followed all day, every day, as it does not include any restriction of foods, but is a sustainable way of eating for life. (6)

BANT produce a Beat the Bloat plate which follows the principles of the Mediterranean diet and is a useful guide to help you follow this dietary pattern:

Fight the fat beat the bloat infographic to support healthy weight loss


Specific weight-loss goals, or those with an existing medical condition require an individualised approach. Please contact me to see how I can support you to make the changes you desire


1. Kim JY. Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance. J Obes Metab Syndr [Internet]. 2021 Mar 3 [cited 2022 Dec 29];30(1):20. Available from: /pmc/articles/PMC8017325/

2. Ebbeling CB, Feldman HA, Klein GL, Wong JMW, Bielak L, Steltz SK, et al. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. BMJ [Internet]. 2018 [cited 2022 Dec 29];363. Available from: /pmc/articles/PMC6233655/

3. Zhu R, Fogelholm M, Poppitt SD, Silvestre MP, Møller G, Huttunen-Lenz M, et al. Adherence to a plant-based diet and consumption of specific plant foods—associations with 3-year weight-loss maintenance and cardiometabolic risk factors: A secondary analysis of the preview intervention study. Nutrients [Internet]. 2021 Nov 1 [cited 2022 Dec 29];13(11). Available from: /pmc/articles/PMC8618731/

4. Greger M. A Whole Food Plant-Based Diet Is Effective for Weight Loss: The Evidence. Am J Lifestyle Med [Internet]. 2020 Sep 1 [cited 2022 Dec 29];14(5):500. Available from: /pmc/articles/PMC7444011/

5. Gregor M. Daily Dozen – Poster Imperial.pdf [Internet]. [cited 2022 Dec 29]. Available from:

6. Muscogiuri G, Verde L, Sulu C, Katsiki N, Hassapidou M, Frias-Toral E, et al. Mediterranean Diet and Obesity-related Disorders: What is the Evidence? Curr Obes Rep [Internet]. 2022 Dec 1 [cited 2022 Dec 29];11(4):287. Available from: /pmc/articles/PMC9729142/

7. BANT Wellbeing Guidelines – BANT [Internet]. [cited 2022 Dec 29]. Available from:

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