It is now well established that people who work on night shifts have an increased risk of heart disease, diabetes and yes … obesity. A recent study analysed the biological changes that occurred in volunteers who were subjected to the same sleep disruptions that night-shift workers experienced. It showed that they had decreased levels of leptin, the hormone that is the master controller of your weight.7 Normally, leptin levels fall when we are dieting; this then causes the increased appetite and decreased metabolism required to protect the body against further weight loss. However, in the subjects who were exposed to night-shift changes in their sleeping patterns, there was no preceding calorie restriction or weight loss triggering the lower leptin levels. The cause of the leptin drop was purely a disruption in their sleeping pattern. The lower leptin levels therefore worked not to regain any weight that had been lost – but to stimulate weight gain by elevating the set-point. In addition, the scientists found that the night-shift experiment increased levels of both insulin and cortisol. The same stress hormone that can lead to a new student’s weight gain was sky-high in night-shift workers.
Night-shift work ➞ lower leptin ➞ higher insulin (leptin resistance) + higher cortisol ➞ HIGHER WEIGHT SET-POINT
I have several patients who had taken on high-flying jobs in multinational companies. These jobs ratcheted up the amount of stress in their lives, but equally importantly involved regular long-haul flights and therefore repeated disruption of their sleeping patterns. Just like the night nurses, their weight set-point elevation corresponded to the time that they started their new high-powered job.
The Third Eye
What causes the profound metabolic changes associated with sleep disruption? Why does the weight set-point become elevated in night-workers or jet-setting business executives? It has long been known that the hormone melatonin, secreted in response to fading light and to darkness, is responsible for our day–night cycle and is the reason animals get sleepy at night and wake up at sunrise.fn2 Recently it has become clearer that melatonin is involved not only in our sleepiness or wakefulness but also in our metabolism.
Melatonin is produced by the pineal gland (named because it resembles a miniature, 5mm pine cone) which sits just behind our eyes. The pineal gland is basically a light-sensing organ, linked by nerve impulses to the eyes. When a lack of ambient light is sensed by the gland, it will release melatonin. This is our sleepiness hormone, our ‘third eye’, which senses when the light is fading and readies our body for sleep. Our pineal gland therefore makes light (or a lack of it) an important neurobiological agent.
There is growing evidence that melatonin not only acts to promote sleepiness, but also has important metabolic effects, including an increased sensitivity to leptin and a decrease in cortisol.8 If we are sensitive to leptin, our weight set-point should stabilize. However, in circumstances where there is a decrease in pineal stimulation, caused by working through the night and trying to sleep during the day (a deficiency of darkness), melatonin levels will be reduced, leading to reduced leptin sensitivity and – you guessed it – a higher weight set-point.
Decreased melatonin ➞ leptin resistance + higher cortisol ➞ HIGHER WEIGHT SET-POINT
The actions of the pineal gland, and melatonin’s effect on leptin, cortisol and metabolism, are still being researched. Some scientists have speculated that the lack of darkness in our neon-lit cities could be having a profound effect on the metabolism of the citizens living in them – with melatonin deficiency contributing to diabetes and obesity.
Passport to a New Weight
The final, but increasingly common, life event that can precipitate sudden weight gain (which I see in patients who have never had problems with their weight before) is migration. Now that we have the mechanical means to ‘fly’, humans as a species commonly migrate to live in places far away from home. However, unlike birds, whose decision to migrate is dictated by the seasons, the human decision to migrate tends to be based on economic or family circumstances. A bird will fly towards an environment that will suit its future health – they are always flying towards summer.
Moving to a different country clearly has an effect on the environmental clues that your brain is searching for in order to calculate the safest quantity of energy reserves for the future. Are you moving into an environment where a famine or a food shortage is going to be more common? Are there signals that a long winter is approaching?
I have seen many patients who migrated from Asia or Africa to Britain and started to gain weight. Some of them gained weight immediately, others after a few months or years. The weight change usually started when they switched from their traditional foods to a more Western diet. Similarly, many patients who travelled from the UK to the USA put weight on: typically their weight increased and then settled at their new ‘American weight’. Interestingly, in the patients that made the move back from the US to the UK, their weight settled back down to their ‘UK weight’. Americans who migrate to Dubai lose weight, but the British who travel to work in Dubai gain weight. And even within countries weight change can suddenly occur: Indians who had previously lived in a rural environment and then migrated to work in the cities complain of weight gain.
In most cases, people who move to an environment where there is a Western diet will be at risk of an increase in their weight set-point. What I find interesting is that there seems to be a hierarchy in the areas that have Western food available (probably determined by the omega profile of a country’s food). America is at the top: people who migrate there will increase their weight and people who leave will decrease their weight set-points. Next is the UAE, followed by northern European countries, then southern Europe, then big cities in the developing world, like Mumbai or Delhi.
We discovered in chapter 9 that most populations which are exposed to a Western diet will have a significant deficiency of the essential fatty acid omega-3 and a massive excess of omega-6. This is largely because fast foods and all processed foods have low omega-3 and high omega-6. A population that is exposed to these types of food will develop cell membrane changes that mirror the ratios of these fatty acids in the food supply. These changes can raise the weight set-point in those people who are genetically susceptible (the Labradors, not the greyhoundsfn3), leading to weight gain.9 In others, the cell membrane changes that the Western diet causes may not lead to weight gain but may trigger other modern diseases such as arthritis and heart disease.
The concept that the omega-3 to omega-6 ratio of a country’s food is mirrored by the ratio in the cell membranes of their population fits in with patients’ observations. Patients suggest that when they move to a new country, their set-points alter, according to their exposure to the Western diet. Although people in Europe, the USA and the UAE all consume a ‘Western diet’, the constituents of the diet will differ: for instance, in the USA 70 per cent of the calories consumed are from processed foods.10 Anyone who has travelled to the US will know how difficult it is to eat healthily. In the UK, 50 per cent of the food consumed is processed. If you travel to other parts of Europe the percentage is lower: 46 per cent in Germany, 35 per cent in Austria, 20 per cent in Slovakia and 13 per cent in both Greece and Italy.11
As the immigrant assimilates the omega fatty acids of the new country’s food into their body, the omega-3 to omega-6 ratio in the food and the omega ratio of their cell membranes become identical. If the new country’s food has a higher omega-6 to omega-3 ratio (i.e. more processed and fast food is available than in the country of origin), then the immigrant’s weight set-point will rise. If the new country’s omega-6 to omega-3 ratio is lower than their country of origin (less processed food), then that person’s weight set-point will decrease. Our patients describe their weight settling either upwards or downwards depending on the quality of the Western food in their new environment. This usually takes several months as the dietary changes become embedded into cellular metabolism.
High processed-food intake = high omega-6 to omega-3 ratio in food �
�� high omega-6 to omega-3 ratio in cell membrane ➞ higher insulin resistance + more leptin resistance ➞ HIGHER WEIGHT SET-POINT
The Microbiome and Weight Loss
If our external environment has such a profound effect on our weight set-point, what about our internal environment? There has recently been a lot of interest in the microbiome, those billions of bacteria (as well as fungi and viruses) living within our guts. Could these affect whether we gain or lose weight easily?
Since 2014 scores of articles have been published in scientific journals linking changes in the make-up of our gut bacteria to obesity. However, the study of the microbiome is very new and we need to approach this new science cautiously and with an open mind. We certainly know that our gut bacteria can have a profound effect on our health, as we know only too well if we suffer a bout of gastroenteritis. The association between a single bacterium (E. coli, for example) and the symptoms of gastroenteritis is obvious. But what if we decided to look at the relationship between the relative populations of 1,000 different bacterial species in our guts and link it to obesity? We suddenly have a large tangle of bacterial data and an outcome measure (our weight) which is not binary (there is no definitive answer as there is with the symptoms of gastroenteritis). Mix into the pot the fact that many studies have been discredited because of contamination and things start to get confusing.
In addition, gut bacteria are affected by the types of diet that we eat. If we eat a typical Western diet that is low in fibre, then the microbiome in the gut will have less diversity. Therefore, to conclude that changes in gut bacteria cause obesity you need to somehow separate the two facts that a Western diet causes obesity, and also that a Western diet causes changes in the gut bacteria. An impossible task!
So why has so much scientific and media interest been focused on a possible link between the microbiome and obesity? A trip to any health-food shop may clarify things. Large sections of these stores are now dedicated to the sale of probiotics – capsules containing bacteria that scientists tell us are good bacteria. In 2016 the probiotics industry was valued at $4 billion. By 2022 the microbiome market, encompassing research and development, plus treatments in the form of probiotics, prebiotics and medical foods, is projected to be valued at $6.9 billion. This new industry, fuelled by self-funded research and the interest of our inquisitive media, is growing at over 9 per cent per year.
I am sure the microbiome will play an important role in our understanding of many diseases in the future, but at present there is no reliable evidence that it has a direct causative effect on our weight set-point.
The Only Way to Lose Weight: Lower Your Set-Point
I hope that it is clear now that sustained weight loss can only be achieved by lifelong eating and lifestyle adjustments – changes that will lower your weight set-point and give you a better quality of life.
Now that you understand the basic principles of the weight set-point (how it goes up or down in response to signals from your diet and environment), we can start to plan the changes that will suit you as a person.
In the final part of this book we will examine in more detail how you can lower your weight set-point by altering:
Your environment and psychological health
Your food and eating habits
Your activity and lifestyle.
Throughout this book we have discussed how sugar and highly refined carbohydrates (such as bread and pasta) give us a great feeling. We are hard-wired for sugar to give us a similar euphoric feeling to that of a drug addict after a hit. It’s not our fault, that’s just how we evolved. It is for this reason that many people suffer with a kind of addiction to the hedonic, pleasurable feeling that foods containing sugar and wheat give us. These food addictions can be difficult to conquer and it is for this reason that I have included a section on psychological techniques that can help you, contributed by a bariatric psychologist.
Part Three
* * *
BLUEPRINT FOR A HEALTHIER WEIGHT
The Secret to Lasting Weight Loss
FOURTEEN
Prepare to Do It Yourself
Preparing Your Home and Mind
One of my biggest nightmares, one of the most frustrating parts of my life, is DIY. Despite being a surgeon, and therefore being good at using my hands, I seem to have great difficulty with even the simplest of DIY jobs. A weekend trip to IKEA sends me into a cold sweat. In the shop the furniture looks Scandinavian, stylish and simple, but once I make the mistake of buying it – and empty the contents of the box (hundreds of different nails, screws and washers; scores of different shapes and sizes of wood) – I am reminded why I don’t visit regularly (despite the tasty canteen meatballs). After several hours on my knees, or adopting various different Twister-type positions to fix screws into annoyingly difficult places, I realize that I have not read the instructions properly – and have to start again … When I finally finish constructing the new cabinet I find that, suspiciously, there are still some screws left over that should have been used. The function of these screws becomes apparent a couple of years down the line when the cabinet door dislodges … and just as I try to fix it back on … a leg falls off.
But when I think back to my DIY disasters I realize the simple mistakes I keep on making: not reading the instructions properly, not taking the time to prepare, being rushed and, most importantly, not having realistic expectations (i.e. thinking a complex cabinet can be knocked up quickly).
Prepare to Reset
In this chapter, we are going to look at the necessary preparations to change your weight set-point. As with a complex DIY task, unless you prepare the groundwork for the job ahead, it is likely to end in failure or disappointment. The aim is to alter small parts of your environment and also the way you live, your habits. These changes will be sensed by your weight-control centre – and your weight set-point and then your weight will drop.
What you need:
Realistic expectations
An understanding of how to fix the problem
A prepared home environment
Time.
Realistic Expectations
A crucial part of the preparation for losing weight, and keeping weight off in the long term, is to have realistic expectations. The success of your efforts to lose weight will be determined by how honest you are with yourself as to what can sensibly be achieved.
If you have gained a lot of weight during your adult life, then it is unlikely that, even with optimal lifestyle changes, you will be able to reach the weight you were at the age of eighteen as your body will be biologically different. If you have very strong obesity genes, if you are from a ‘big’ family, then again it is unlikely that you will become slim. An expectation to lose some weight and be healthier and happier is much more achievable.
As we have learned, everyone is different when it comes to their propensity to gain weight in a particular environment. And the same can be said when we put in place habits and changes to our environment that will lower our weight set-point. The main expectations that you should have when you make these changes are that, yes, you will lose weight, but, just as importantly, you will be much healthier and will live a longer and happier life as a result. Try and focus on your improved health and happiness just as much as your improved waistline when you are visualizing your life in the future. Don’t get frustrated if you don’t reach your weight-loss target. It may be that it was unrealistic. Or it may be that you have not allowed enough time for the changes to work through your body.
Unlike a short-term dietary fix, this programme will build momentum and become more and more effective as time goes by, as you embrace a lifestyle that suits you and insulate your body from the dangers out there in the environment.
Some patients do come to me for bariatric surgery with unrealistic expectations, however. Maybe they weigh 120kg (19 stone), but they say they will only be happy if they can reduce their weight to 60kg (9 stone 6lb) – they want to be skinny, even though they are mi
ddle-aged and have never been remotely slim in their lives. If you have the surgery, I tell them, your weight will reset to 80–85kg (about 13 stone) – not 60kg. If they go ahead with unrealistic expectations, then even if the surgery is successful, even if they reach the anticipated 80kg, they will be disappointed and may see the procedure as a failure. So realistic and open expectations are the key to success.
Understand How to Fix the Problem
If you are serious about weight loss you should not skip immediately to this part of the book and start the programme. First, you need to understand how your weight is controlled and how your body interacts with your environment for it to work. It is crucial to understand the concept of the weight set-point – this will be the key to your success. In the same way that you need to study and understand the instruction manual before you begin to construct a complicated piece of furniture – otherwise it might end in frustration – so you need to understand this new concept of weight regulation before starting the programme. If you feel it is not clear to you yet, go back to Parts One and Two to refresh your understanding of the problem and the solution.
Prepare Your Home Environment
We know that when people move from one country to another they take on the imprint of that country’s food within their bodies. Even if we try to eat in a relatively healthy way, the country’s food and food culture will still prevail. The main purpose of this book is to enable you to sustain weight loss by decreasing your set-point. This can only be done by changing the environmental signals that you are receiving. None of us really want our bodies to experience the full Western food (and stress) experience as this is what has poisoned it and led to the metabolic chaos, resulting in excess weight and obesity.
Why We Eat (Too Much) Page 26