In January 2020, Dr Andrew Jenkinson published his best-selling book - ‘Why We Eat (Too much)?’ – in which he outlined the emerging new science behind weight loss and explained why so many people fail to lose weight through dieting. Now, in three fascinating interviews with Dr Georgios Dimitriadis, they explore the new and emerging science of obesity, disassemble the set beliefs and stigma surrounding obesity and ask - has medicine and society been looking for the causes of obesity in the wrong places? In an exclusive interview with Bariatric News, we asked them what are the biggest misconceptions about obesity, whether science and medicine must now rethink the root causes of obesity, and ultimately, what do these new discoveries tell us about how we can treat this debilitating disease?
"It’s not the calories in the food. It’s what the food does to the body.” - Andrew Jenkinson
“I think, like all bariatric surgeons, I got into bariatric surgery without really understanding the science behind it. I was treating patients, but not really understanding the condition,” explained Dr Jenkinson, Consultant in Bariatric & General Surgery at University College London Hospital. “I began to ask myself why would a patient want to have part of their stomach removed or bypassed, rather going on a diet or to the gym? Almost all my patients had the same story: they have lost weight through diet and exercise only to put the weight back on. I wanted to know why they were unable to keep the weight off. There was a disparity between what my patients were telling me about their weight journey and our conventional way of thinking about obesity – ‘calories in, calories out’. So really, the book was inspired by my patients.”
With many of his patients telling the same story, he became convinced that their inability to maintain weight loss was due to their metabolism. Over the next few years, he attended many metabolic conferences and conducted his own research to examine and understand what were the metabolic changes caused by obesity and how these changes negated the impact of diets on weight loss.
“It became clear to me that everyone has their own individual weight set points and that is something that is determined quite a lot by your genes. For example, some 70% of where that weight set points is going to be is genetically predetermined. The trigger for the weight set point is a patient’s environment such as food type, stress, sleep quality, etc. Therefore, a patient can lose weight but they are fighting against their bodies own weight set point, and this is why they regain weight.”
He explained that another big area of misunderstanding is metabolic adaptability, where our basal metabolism is reduced after dieting. However, the body adapts to the changes in calories and for many patients despite them complying with the diet, their metabolism adapts to it – they don’t lose any more weight, they feel tired etc. and the weight loss will plateau. In addition, their GI hormones such as ghrelin, are urging them to consume energy dense foods. Due to evolutionary processes – your body perceives the reduction in calories as because you're in an environment where there may be food shortages. Therefore, as a survival instinct your body will want extra calories stored, as an insurance mechanism. Conversely, he explained that the opposite is also true – that when were are overeating our body can increase its metabolic rate to prevent excess weight gain.
A third area or interest to Mr Jenkinson was leptin resistance, in which the brain does not respond as it normally would to leptin, so there is a weakened signal to the hypothalamus that there is enough energy stores available. Therefore, people who have leptin resistance eat more even though their body has enough fat stores.
“The key mechanism behind leptin resistance is the presence of insulin, we know that insulin stimulates leptin secretion through a posttranscriptional mechanism. We also know that obesity can cause insulin resistance, where the pancreas continues to produce insulin but the peripheral cells have become resistant to it, and so a vicious cycle of gaining weight and becoming increasingly leptin resistant begins.”
“We know that patients who have obesity and patients with obesity and diabetes produce fewer gut hormones in response to the intake of carbohydrates. As you produce fewer of these appetite hormones, your sensation of fullness is impaired, so you're more likely to need to eat more to feel satiated,” explained Dr Dimitriadis, Consultant in Endocrinology and Obesity Medicine at King's College Hospital NHS Foundation Trust. “This is one of the reasons we see patients with obesity putting on more weight, gradually gaining more and more weight, and there's no end to it. That's why diet fails, they're not sustainable as your body adapts to the diet. The diet stops being effective at some point, and once again you will gain more weight, because your body has adapted to its previous state. There is an impairment between the gut and the brain. As a result, a person living with obesity requires an intervention such as bariatric surgery or pharmacotherapy, to fix the impairment between the gut and the brain.”
He believes that education is the key is breaking the increasing rates of obesity, educating both healthcare professionals and the public.
“For a healthcare professional, the problem begins with training, we are not taught to see obesity as a disease, and this is the start of a domino of misconceptions, I believe. These misconceptions are then passed on to the public and the media and are then re-enforced. Another issue is a lack of education about obesity for the healthcare professional. If you are interested in obesity and want to know more, you have to do your own research there as there are very few structured training programmes to support you,” he added. “It is not just the healthcare professional we need to re-educate, but also the public. For years, we have had a continuous message to eat more vegetables, more fruit, but the scientific messages, around obesity being driven by something more than simply a lack of exercise or a bad diet, doesn’t seem to be getting through.”
Obesity is a disease
For Dr Dimitriadis, there is no doubt that obesity should be seen as a disease, not as a choice, not as a social problem. He said society as a whole needs to change the mindset that people with obesity are glutenous, lazy, lack willpower, they don't.
“Obesity is a disease, it actually fits the criteria, the definition of a disease, and it has been recognised as a disease by many different professional societies and in many countries. We shouldn't just focus on prevention. Focusing on prevention is important, but we have a very large population of people who actually have the disease now, and we need to do something about that. So, we need to focus both on prevention and treatment. We need to make an effort to find parameters that will help us predefine response to treatment, but also to predefine the severity of the disease and define who needs the treatment the most.”
He added that because obesity is not recognised as a disease, patients with obesity are not being treated. They're not seen as having a problem and as a progressive and chronic disease, obesity if left untreated, it will result in further problems in the coming years.
“I think education is crucial and we need to educate people about food and what food does to people metabolically. The food that we eat today – fast food, snacking food etc are all rich in processed fats and sugars and they are like a drug – they make you feel good, but actually, the side effect of what is in the food – is the impairment of the body’s signalling systems that control appetite,” warned Jenkinson.
Another societal aspect impacting obesity is stigma, which for a person living with obesity is ‘everywhere’, explained Dr Dimitriadis.
“Obesity stigma impacts their daily lives - whether it is finding the appropriate seat when they come to the hospital or job opportunities, or finding a partner – obesity puts people at a disadvantage. I think the main disadvantage is the opinions others can have, such as that the person is lazy or lacking willpower. This has a psychological impact, it hampers confidence and those actually living with obesity often get to the point where they those sorts of opinions are right. A kind of self-stigmatising. Obesity is such a visible disease. You can't hide it. It's not something you can just cover up. It changes people’s mental health and ends up decreasing people's enjoyment of life massively.”
According to Mr Jenkinson there are currently three very effective procedures to treat obesity and diabetes - the gastric bypass, the mini bypass (or OAGB) and gastric sleeve. Both bypass procedures are the most effective particularly for Type 2 diabetes, and although the sleeve it least effective, in his opinion, it is still effective and is associated with fewer risks and complications.
“For a patient who is diabetic, a bypass or mini bypass is my preferred option, but Type 2 diabetes can be treated with a sleeve. However, each procedure is considered in conjunction with the patient’s comorbidities in mind. For example, if a patient has gastric reflux sometimes a sleeve can worsen the reflux. I think around 5% of sleeve patients get significant problems with reflux so it is important to discuss all treatments option with patients and inform them of the positive and possible negative outcomes from bariatric surgery.”
Ultimately, he added, this comes down to improving our understanding of which patients will respond best both surgical and the new generation of pharmacotherapy treatments.
“All bariatric procedures are effective, but we do not have the research to reliably predict which procedure works most effectively in which patient. The evidence demonstrates patients with Type 2 diabetes are more likely to achieve remission following bypass surgery, especially if the duration of type 2 diabetes is less than ten years and if they're not on insulin before surgery. In addition, younger patients also have fewer complications,” explained Dr Dimitriadis. “We also know that metabolic procedures - such as the bypass - produce metabolic benefits, independent of weight loss, such as direct effects on the myocardium in the heart and might actually be cardio-protective, again independent of weight loss.”
The same, he added, can be applied to our knowledge of pharmacotherapy as there are no reliable ways of identifying who is the best candidate for which pharmacotherapy. Research is continuing to examine different metabolic markers, circulating biomarkers, including exosome non-targeted multi-omics, micro-RNA changes and others that can predict the response.
“We are getting there, we do have some parameters we can use to predict response and there are certain bariatric procedures that are more suitable than pharmacotherapy in certain patient cohorts. In my view, we can use multiple treatments for obesity, similar to how we treat cancer. So, using pharmacotherapy in addition to surgery, we can for example reduce our patients’ medical problems such as reducing the size of the liver, improved cardio-metabolic health - before bariatric surgery. Pharmacotherapy can also be used also as adjuvant treatment for people who still require support after bariatric surgery,” Dr Dimitriadis concluded. “So, in my opinion, combining treatments, combining specialities, gives the best outcomes until we have a better understanding, and we can tailor treatment, which I think is the way forward, especially within the NHS. We must tailor treatment because we don't have the resources to offer treatment to everyone.”
To watch all 3 episodes of ‘Obesity: The Big Truth’, please click here
For more information about the best-selling book, ‘Why we eat (Too much)’, please click here