The Miracle Pill

by Peter Walker

  Numerous studies have demonstrated Mayer’s maxim that the body tends not to limit its appetite when daily movement is reduced. One particularly thorough Scottish project involved taking six healthy if generally inactive men in their early twenties and essentially treating them as laboratory rodents for two seven-day periods. They spent each week in what is known as a ‘whole body calorimeter’, a sealed-off, space age–looking pod inside of which the oxygen they consumed and the carbon dioxide they produced could be measured, which allowed an accurate calculation of their total energy expenditure. On both weeks, the volunteers were able to eat however much food they wanted at three set meal times, chosen from a menu. The food was delivered via an airtight hatch, a process which must presumably have increased the lab rat ambience all the more.

  The difference between the weeks was that in one of them, each volunteer was instructed to be inactive, limited to a total daily exertion of just 1.4 of their basal metabolic rate (BMR), or resting state. If you remember this from Chapter 2, a figure of 1.4 puts someone in the more-or-less completely sedentary category, only slightly above a patient in a hospital bed. On the other week – the order of the weeks was randomly chosen and the subjects were not told the purpose of the experiment – the volunteers were instructed to carry out three exercise bike sessions a day in their sealed pods, pushing their total daily energy expenditure to 1.8 times BMR, the sort of figure you might see in a manual job.

  Although there was, as you would expect, considerable difference between the energy expended in the active and sedentary weeks, the researchers found that food intake was broadly similar for both. The volunteers did consume slightly more calories during the active phase, but this was due to a greater intake of caloric fluids like soft drinks. There was also, the academics noted, ‘no tendency for energy intake to drop as the sedentary regimen progressed’.

  The extent of excess eating during the artificially immobile week was striking. The average combined excess energy balance for the test subjects over the sedentary seven days was just over 3,600 calories, sufficient for a massive 25kg in weight gain if maintained over a year. Interestingly, the experiment found that the subjects also ate slightly more than they needed during the active period, albeit only slightly, a result which might, of course, simply demonstrate the habit of many young men to eat as much food as they can if it is available without effort or cost.27

  This imbalance between intake and exertion is a fascinating area, and can vary greatly between different people. Another study put a group of men and women through three progressively more intense exercise regimes over a sixteen-day period using stationary bikes or treadmills, again comparing their energy output and food intake. This showed two things. One was the body’s general tendency not to fully account for extra exertion – on average the test subjects only made up 30 per cent of the increased energy they expended in additional food intake. The other was that this was by no means a uniform effect. About half the group ate more, and the others didn’t.28

  This shows the split between what researchers call ‘compensators’ and ‘non-compensators’. While I don’t wish to create any new artificial divisions in an already atomised world, in much the same way as you can divide people into, say, those who believe it’s acceptable to recline an airline seat on a short-haul flight and those who argue that this should be punishable by prison, the idea of compensators and non-compensators does resonate very strongly. I firmly fall into the former camp, as someone who both enjoys staying active but also does so as a way to enjoy more of the foods I love, in the belief it will not affect my body composition (as you will see later, this has not proved an infallible maxim). It’s not that I think people who feel differently are wrong, just that they appear to be speaking a slightly different physical language.

  Worshipping the scales

  All these studies point fundamentally towards the same conclusion. Irrespective of modern dietary changes, the much-proved reduction in overall average physical activity around the world plays a very significant role in the parallel crisis of obesity. The health risks of obesity cross over significantly with those of inactivity, but are not precisely the same, both in terms of scope and intensity.

  In the previously mentioned textbook chapter about obesity co-authored by Robert Ross, there is an eloquent chart citing various health conditions associated with excess weight, with between one and four upward-pointing arrows showing the degree of risk associated with obesity. One arrow indicates an increased risk of 25 per cent–50 per cent; two means a 200 per cent increase; three arrows is around 350 per cent; while four stands for more than 400 per cent additional risk. The four-arrow warning is given to type 2 diabetes, while three arrows is next to pulmonary embolism (a blood clot in the lungs), arthritis and chronic back pain. The two-arrow designation is given to coronary artery disease, high blood pressure, kidney and pancreatic cancers and gallbladder disease. In the final, one-arrow group, come asthma, colorectal cancer, breast cancer in older women and the big ones – stroke, heart failure and early death.29 This is, of course, in part dependent on the extent of weight, with numerous studies showing that once BMI hits around 30, or especially 40 (the threshold of severe obesity), the risks multiply.

  There is also the parallel issue of morbidity – someone’s ability to live independently and in good health. One US study which measured the changing health outcomes from obesity over fifteen years noted that while death rates had actually fallen, this could be largely because of improved medical care, and that the amount of impairment and disability caused by excess weight was both increasing and taking effect in people from an ever-younger age.30

  There is another big subject to consider with the health risks of weight: it depends where the weight is. Increasing amounts of research have shown the particular importance of fat around the waist. Visceral, or intra-abdominal fat, makes up just 10 per cent or so of your body’s total fat content (the rest is subcutaneous fat, the layer just below the skin), but is the focus of many health worries. These are fat cells in the visceral peritoneum, the inner layer of a membrane wrapped around internal organs like the liver and stomach. Quite why visceral fat is so risky is not completely understood. One idea, known as portal theory,31 argues that visceral fat transmits substances which can promote inflammation to the liver via the portal vein. This can cause insulin resistance, as well as liver steatosis, otherwise known as non-alcoholic fatty liver, which has a series of potential health consequences of its own. Another idea is based around visceral fat’s role in releasing cytokines, molecules which transmit signals to cells and can also provoke inflammation.

  This is why obesity experts increasingly use measures such as waist size, or a waist-to-height ratio, as a gauge of the potential health risks of excess weight, rather than BMI alone. BMI can be a blunt tool, not least as it doesn’t distinguish between muscle and fat. Thus, as some rugby players will tell you at great length, it is possible for a hugely fit and very built-up professional athlete to have a BMI above 25, officially making them overweight.

  Robert Ross is the lead author of a statement released in 2020 by more than a dozen experts in the field that advises governments and medical practitioners to focus less on BMI and more on waist size. ‘Decreases in waist circumference are a critically important treatment target for reducing adverse health risks for both men and women,’ it says. The paper warns that while BMI measurements are starting to plateau in some countries, waist circumference figures appear to still be on the increase, potentially masking the extent of the obesity-related health crisis.32

  Ross told me that he is a firm believer in the value of waist size as a guide to weight-related health: ‘Our evidence would clearly suggest that you can reduce your waist circumference without substantial reductions in body weight. Now, if you’re losing weight, I’ve never seen anybody gain in the waist. I, myself, use my pant size. I haven’t been on a scale in, seriously, thirty years. I’ve got no idea. My pants tell me how I’m doing.’ BMI
remains a useful measure, he stresses, just ideally not used on its own: ‘I’m not one that promotes drop-kicking BMI into the Atlantic Ocean. If you want to stratify an adult’s obesity-related health risk, then measure both.’33

  Waist circumference is a particularly important measure in the rise of type 2 diabetes, which is the condition that most closely connects inactivity and obesity, and forms perhaps the greatest part of the resultant global public health crisis. Estimates suggest almost one in ten of the world’s population is living with diabetes, the vast majority of them the type 2 variant and with almost half of them, as happened with Tom Watson, doing so with the condition undiagnosed. Taking into account undiagnosed cases, anything up to 4 million Britons have it.34 And the risk from excess weight is proved beyond doubt. The mechanism is complex and still not fully understood, as we saw in Chapter 2, but seems driven by the increased presence of cytokines and other substances associated with inflammation, which can provoke insulin resistance.

  Again, much of this is connected to visceral fat, hence the importance of waist size – something shown in numerous studies. One major European research project which tracked more than 25,000 adults over an average of nine years found that each centimetre increase in waist size brought an 8 per cent increase in the risk of diabetes. Strikingly, the researcher found that men and women with a normal BMI of below 25 but an unhealthy waist circumference had a 3.6 times increased risk of developing the condition, more than the 2.6 increase faced by those with a BMI of between 25 and 30 but a healthy waist size.35

  There is also strong evidence about the more general health risks of an increased waist size. One 2014 meta-study, which pooled data from more than 650,000 adults of all ages over an average of nine years, found that after factoring out other circumstances, a higher waist circumference was linked with a greater risk of death at every level of BMI, from 20 to 50. This meant, the authors noted, that even in people of what is seen as a normal weight, waist size should be monitored as a potential health risk.36

  Another issue with a fixation on BMI is that, as we shall see soon, losing weight via increased activity can be a long, arduous and often dispiriting process. But even if someone’s BMI remains stubbornly consistent, their health could still be improving, with a decrease in waist circumference often indicating this. ‘Anecdotally we hear that all the time,’ Robert Ross says. ‘Someone will come up and say, “Gee, Dr Ross, I’m not losing the weight that I wanted to despite my good eating habits and physical activity. But interestingly enough, this dress fits a lot better, or my pants fit a lot better. It’s just the darned bathroom scale.” I joke that Moses came down the mountain with two tablets and a bathroom scale. We worship that thing. Some people get on that scale and if it doesn’t say what they want, they feel poorly about themselves, despite engaging in healthy behaviours. And that’s so unfortunate, truly a missed opportunity.’

  So what is a healthy waist size? As with BMI, this is to an extent approximate, and also like BMI it varies across ethnic groups. But for white adults, the metric first devised in 1995 by the pleasingly named Professor Mike Lean of Glasgow University, and still seen as the standard, suggests that, irrespective of your height or BMI, a waist size of more than 37 inches (94cm) in men and 31.5 inches (80cm) in women is potentially unhealthy and should be reduced.37 Once you get above 40 inches (102cm) for men and 34.5 inches (88cm) for women, NHS guidance says you are ‘at very high risk of some serious health conditions and should see a GP’.38 The figures are again slightly less for people of South or East Asian background, with the health risks seen as starting at 35.5 inches (90cm) in men and 31.5 inches (80cm) in women.

  As Robert Ross noted, the relevance of waist size to activity is that people tend to see the effects much more quickly than they do with BMI. When it comes to weight loss, many are surprised to learn quite how much exertion is needed to achieve this, without a parallel programme of diet control, or even how much is recommended if your only goal is to stay roughly the same weight. Yes, the government-recommended level of at least 150 minutes a week of moderate activity or equivalent will provide almost endless health benefits. But weight loss – and perhaps even weight maintenance – will probably not be among them.

  A statement released almost twenty years ago by a series of leading experts in the field of activity and weight laid out what is generally seen as the consensus view: even to remain the same weight, people need to aim for at least forty-five to sixty minutes of moderate exertion a day, every day. If someone was obese and had slimmed down, an even greater amount of movement is needed to stay slim – anything from sixty to ninety minutes a day.39

  So how much activity is required to lose significant amounts of weight, without a parallel change in diet? To answer this we must turn to perhaps the most fascinating and also one of the more alarming studies ever carried out in the field of physical activity research. It took place in Bulgaria in 1982, and the resulting full academic paper – nowadays so rare I had to order a copy from the British Library – certainly has a very Eastern Bloc feel to it.

  Led by the slightly sinister-sounding Institute of Hygiene and Occupational Health in Sofia, it followed the fortunes of thirty-two women who came from what was described as ‘a sanatorium for obese patients’. Over the 45-day course of the study the women lost an impressive average of 12.4kg, about one eighth of their body weight, at the same time seeing their body fat proportion fall from 38 per cent to 31 per cent. This happened while they ate an average of 2,780 calories per day, well over the amount normally needed to maintain weight, let alone lose so much.

  How did they do it? As you read further down the study it begins to make sense. Every day they were put through an exercise programme lasting about ten hours. The daily group regime for the women – who are described as ‘volunteers’, although I have my doubts – comprised this: fifteen minutes of gymnastics; an hour of ‘standing exercises’; an hour of gymnastics using apparatus; two hours of ‘walks and long-distance races’; three hours of ‘sports and athletic games’; and finally an hour of what is described, cryptically and disconcertingly, as ‘therapeutic dances’. In addition, the women did individual exercises including swimming, tennis, and more ‘long-distance races’. If that was not enough to break their spirit, there was also a weekly ‘walking tour’ of an initial 20km, a distance which increased by 5km every week.

  The result, the study boasts, was ‘statistically significant decrease in weight and percentage of body fat’. This is perhaps not surprising, given it also found that the participants expended an average of 3,700 calories per day.40 As a comparison, a 2019 study of footballers in the Dutch premier league, the Eredivisie, discovered their average daily physical exertion was a mere 3,300 calories.41 As a regime, this punishing exercise programme definitely shed the weight. But it is perhaps not so straightforward, let alone appealing, to transfer into everyday life.

  The right message

  The message thus seems fairly clear. Unless you are able to clear your diary for the foreseeable future to incorporate a pretty extreme activity regime, should your goal be to lose a lot of weight then you will need to address your diet as well as physical movement. Again, I’m not about to get into how weight loss can best be achieved, but it is worth stressing that it tends to be pretty challenging, as is maintaining the loss. Numerous studies have examined the issue of weight recidivism, and the consensus seems to be that over a period of year or so, the majority of dieters regain some or all of what they lost. Much of this seems to be the body’s innate resistance, built up over millennia of coping with food lack rather than excess, to oppose repeated negative energy balances, fighting back with metabolic changes, for example to boost the appetite.

  Tom Watson’s book is a useful chronicle of the sheer effort required to shed significant amounts of weight in a fairly brief time. A self-professed borderline obsessional character, Watson read endless scientific studies on diets, completely cut out sugars, and bought a set of electronic scal
es which he synchronised with his mobile phone to get the satisfaction, as he put it, of ‘watching the graph going down over time’. As well as completely reshaping what he ate, his activity regime included not just walking, but increasing amounts of cycling, and visits to a series of gyms. For one particularly rigorous period he lifted weights three days a week in what he calls ‘an extraordinarily expensive’ gym. ‘The results were amazing,’ he says. ‘I described it as getting a body I didn’t deserve in a gym I couldn’t afford. But for those two months the whole world revolved around the gym and nutrition in the gym. And that wasn’t my goal.’

  Watson’s gym regime also highlights the increasing focus on weights-based activity, as well as aerobic exertion, as a way to combat excess weight, even though the results seem to happen more on reducing waist size and body fat percentage rather than lowering BMI. There is another potential benefit. As some studies have noted, aerobic exercise like running or cycling, even brisk walking, can be difficult for people who are overweight or obese, whereas lifting weights might appear more feasible.

  Some form of lifting weights, whether in a gym or as part of everyday life, also appears especially important in the management of type 2 diabetes, with numerous studies noting that the effects can be as beneficial as those of aerobic activity. Much of this appears to be linked to the importance of our mass of skeletal muscle in bodily health. It is in skeletal muscle where the bulk of glucose uptake after meals takes place, and insulin resistance here appears to be one of the very beginning elements of type 2 diabetes. Working your muscles is also linked to better functioning mitochondria, and the improved processing of fats, both of which reduce the risk of diabetes.