On balance, long-term evidence to advocate these diets is lacking. Essentially, it’s a temporary fix. I appreciate the potential therapeutic value of these diets as a short-term strategy, but personally, I think a diet concentrated on plant nutrition far outweighs one focused on meat. More research is needed to validate the claims of these diets that drastically remove beneficial carbohydrate sources, and the lack of fruit, vegetables and fibre is something that would concern me. We know fibre is essential for proper functioning of our digestive system: our microbes feed off these materials and lack of fibre puts us at risk of bowel cancer.¹¹² For those reasons, I can’t condone low-carb lifestyles long-term, but I don’t doubt that some people have found them beneficial and they may have a role in clinical care.

      SIRT diet

      While I welcome excitement about foods that have the potential to impact our genetic make-up, the SIRT diet’s focus on a small list of foods impacting some genetic pathways detracts from how multifaceted and complicated human nutrition is. ‘SIRT’ genes are what this diet is named after and increasing the activity of these genes (and the proteins they code for) is thought to reduce inflammation, control blood sugar and has been linked to reducing cancer risk.¹¹³

      Yes, parsley, dark chocolate and green tea all increase SIRT gene expression but they also contain catechins, luteolin and a host of micronutrients that are essential for processes in our body’s cells. As do lupini beans, cavolo nero, broccoli, coriander, chilli and a whole bunch of foods that don’t fit a particular list. I think it completely misses the point to focus on an exclusive group of ingredients, and it doesn’t encourage a healthy relationship with food. Every ingredient deserves a platform.

      Our grocery aisles are lined with unbelievable health-promoting foods, our seasons provide constant variety and our multicultural society introduces spices and herbs from across the planet. As I alluded to in the previous section, we are merely scratching the surface when it comes to the importance of different interactions between ingredients and our genes. I could have quite easily picked out a few fruits, vegetables and spices affecting one of many inflammatory pathways and called it the ‘NRF2 diet’, or how about the ‘TNF diet’? The Telomere diet? Do these sound scientifically valid enough?

      The interaction between food and our genetics is a fascinating field.¹¹⁴ But it is one layer of a multi-faceted process that I haven’t made the cavalier attempt of trying to explain in its entirety. It certainly cannot be explained with one set of genes. Don’t let yourselves be patronised. Our understanding of these pathways is minuscule at best¹¹⁵ … and don’t get me started on ‘juice cleanses’!

      The interaction between food and our genetics is a fascinating field.

      5:2 diet

      The science used to formulate intermittent fasting diets like the 5:2 diet is impressive.¹¹⁶ There appear to be benefits of cyclical fasting,^117,118 but our way of eating needs to be sustainable¹¹⁹ and more importantly, enjoyable. Who wants to endure restricting themselves on a weekly basis … for life? I am convinced that some people have found benefits from this practice,¹²⁰ but if I were to tell the majority of patients I see in clinic to reduce their calories to 500 for two whole days, I know exactly where they’d be telling me to go!

      And this brings me nicely to another topic. I don’t count calories. For the majority of people it’s a complete waste of time because it shifts the focus toward indiscriminate numbers on packets of food and away from what is actually important: the quality of food we introduce into our body. Clearly, a bag of sugar compared to an equal calorie content of spinach is going to have drastically different effects on our body. Calorie counting does not account for this difference. It focuses unnecessarily on a logic that was once thought to be scientifically accurate but is now shown to be flawed in many ways.

       + A NOTE ON CALORIES

      The long-held idea that excessive calorie consumption leads to weight gain and reducing calories leads to weight loss is simply not accurate. Also, the metabolism of food is likely to differ from person to person depending on a host of factors such as their microbiome population, their genes, activity level, timing of meals and many other variables. A 200-calorie lunch isn’t necessarily ‘healthier’ than the 500-calorie one, and two identical calorie meals can have entirely different metabolic effects. The majority of people I see in clinic do not need to diligently measure and obsess about these numbers.

      When we encourage concentrating on calories, or even the Glycaemic Index (GI) of foods, we lose sight of the bigger picture. People find themselves picking up ready-made desserts and putting down bananas. This is madness. There is a huge difference between the metabolic effect of packaged meals and a whole food. Diets that promote this are not educative and they serve to confuse rather than inspire, with dire consequences. Relax, cook as often as possible at home using whole ingredients, and put the calorie counters away.

      Fasting, and the variations of fasting practices¹²⁰, is an interesting area and warrants further research. But, what I think is potentially as effective and easier to incorporate into daily working life is the concept of defined eating periods.¹²¹ A time period during the day when you eat versus a period when you do not eat. Research also shows that the simple effort of ensuring you eat at regular times and within a 10–11-hour window can reduce your risk of diabetes and cardiovascular disease.¹²² It stabilises insulin release and leads to less fat around the organs (which is dangerous). It makes logical sense to me and a lot of my patients are easily able to slot this convenient ‘fasting’ practice into their eating habits that doesn’t require obsessive calorie counting or restriction.

      Alkaline diet

      I’m going to give you some insight as to why there is such a divide between physicians and the wellness industry. When non-medically trained, self-styled, health ‘gurus’ are given a platform to influence people into believing they can change their blood pH with a diet high in alkaline foods, it is incredibly frustrating. You can change the pH of your urine using food, but the suggestion that this diet has a miraculous, transformational total-body effect is a huge oversimplification of the science.¹²³

      Fundamentally, this diet encourages us to eat more dark green leafy vegetables and generally healthier foods, which isn’t a bad thing.^124,125 However, people deserve to be educated and told the truth about how food interacts with our biochemistry, instead of being duped into thinking this is how our bodies work. When you’ve spent time in intensive care, learnt about the complexities of acid-base balance in ill patients and tried to get your head around how complicated pH control is,^126,127 you can understand why the use of alkaline theories to promote products annoy doctors all round. We have intelligently evolved organs that precisely control our blood pH using mechanisms that still continue to amaze me.

      Introducing ‘alkaline’ foods such as brassica vegetables and colourful fruits is fantastic, but rather than just focusing on ‘alkalinity’, we should appreciate the phytochemical content, the fibre and micronutrients like folate and magnesium. We also need to consider the relatively low sugar content and the endless chemicals that we haven’t yet fully investigated. Focusing on ‘alkalinity’ confuses the matter and I fear it will create an obsession among patients akin to calorie counting. I am an open-minded doctor, so perhaps one day we will learn more about ‘alkalinity’, but for now the science just does not support these claims.^128,123,129 I would have great reservations for the liberal use of these ideas, especially by those who cannot appreciate the scientific controversy.

      Low Fat/Slimming World/NHS Choices

      The medical profession’s obsession with reducing the fat content of our food and encouraging processed, low-fat options over the past few decades has probably been the most effective, yet destructive, health campaign of all time. It’s a message I myself have been guilty of promoting. An over-indulgence in calories, particularly from fat, combined with apathy toward exercise was the generally accepted explanation for why patients were overweight and sick. It was arrogant and naïve to accept this assumption that gluttony was the underlying