We are living through an obesity epidemic like we have never known before. Obesity rates tripled in America between 1985 and 2011 and we were not far behind. In the UK, two-thirds of adults and a quarter of children between 2 and 11 years are either obese or overweight. Babies between birth and 6 months are getting fatter. Even the animals we live with are getting fatter (but not wild animals).

Particularly puzzling is the fact that in the UK we are eating 15-30% less calories in 2009 compared to 1980 and yet weight has increased (by 8.6Kg for males and 7.9 kg for females) over this time. So what is going on?

         And yet George Campbell, a South African physician working at the turn of the twentieth century noted the Natal Indians in South Africa survived on a near starvation diet of 1700 calories a day. And yet had many were enormously obese with one third succumbing to diabetes. They worked in the sugar factories and consumed large amounts of sugar. This gives a clue to a major culprit in obesity. (The same Indian population in India had little obesity and diabetes).

         What is causing this epidemic and how do we deal with it? But let’s first look at how we have tackled it so far.


Eat Less, Move More: It Doesn’t Work

In the past 30 years there have been fourteen government strategies on obesity containing 689 policies published in the UK. Most of these policies were of the “eat less, move more” variety. None have worked. Obesity has increased relentlessly over this time.

 Most people who gain weight follow the familiar advice of eating less and exercising more. They go on a diet and they do more exercise. But how effective is this?

We now have large numbers of trials on both adults and children, some massive (eg the Women’s Health Initiative Dietary Modification Trial which followed 50,000 women for seven and a half year and reduced fats by 20% and increased exercise). These all tell the same story. Initially weight is lost (peaking around 6 months) and then weight loss reaches a plateau. Then weight is gradually regained. Often the weight ends up higher than it was before, even whilst eating less.

Many people have told me the same sad tale. “It worked for a while and then I went back to my same old weight or more”. This has been found to be true for nearly all diets whether they be low fat, low calories or the Atkins diet. Basically if you want to lose weight this advice (eat less, move more) is unlikely to work for you. Historically it has been an abject failure.  We need a better strategy.


Ultra-Processed Foods (UPFs)

        Today 57% of the food we eat in the UK is ultra-processed. We are only beginning to recognise the danger from these foods: they are thought to be linked with 22% of deaths in the UK and they are also linked with increasing obesity, cancers, diabetes, heart disease, dementia, inflammatory bowel disease, fatty liver and a range of other conditions.

          In the UK and the USA obesity and type 2 diabetes started to increase in the 1980 and has increased two to three-fold since that time. Before then, type 2 diabetes was never seen in children and adolescents but now it’s not unusual.

In other countries this epidemic started later but increased far more dramatically, shooting up seven-fold in China and some African countries. What causing such a spectacular change?

A ground-breaking study in 2019 gave two groups of volunteers a diet for one month with exactly the same amounts of calories, fats, salt and sugar. One group had ultra-processed foods (UPFs) whereas the other group had the same food cooked from scratch. They could eat as much as they liked. The results surprised even the researchers. Those eating UPFs ate 500 calories more a day and gained weight. Those on the unprocessed diet lost weight.

Ultra-processed foods are industrially-produced substances with complex mixtures of largely synthetic ingredients. Almost any natural ingredient is likely to be replaced with a cheaper artificial one. Most of the ingredients have never been eaten before this time. They would be inedible without the added sugar, salt and flavourings. They disrupt our sense of taste (which is an essential clue to what foods we need to eat) and distort our appetite and are designed to be addictive.

        The evidence strongly suggests that the obesity and diabetes epidemics have been a direct result of the introduction of UPFs. These foods typically contain fructose, artificial sweeteners, adulterated fats which all make obesity worse (see later) plus many other chemicals whose effect are, at present, unknown. It would make sense for anyone with a weight problem to avoid UPFs as much as possible.

        Ultraprocessed foods are defined as foods containing chemicals not found in our kitchens. They are usually wrapped in plastic and contain multiple ingredients. They include ready meals, all fizzy drinks, most juices, most breads and baked goods and multiple other foods. Typically, they are high in sugar, adulterated fats and salt. Emulsifiers or flavourings on the label are a useful warning sign that it is UPF.


The Body’s Thermostat

One thing we know, from both underfeeding and overfeeding studies is that the body always attempts to return to its original weight. In fact, in the short-term it is quite hard to lose weight or to gain weight. It is as if the body has a thermostat which keeps the body at a set weight. But over decades this thermostat tends to go slowly up. But what sets the thermostat in the first place? The main cause is insulin and insulin resistance and this is what we need to understand to have any hope of succeeding with weight loss.

Insulin and Insulin Resistance -The Keys to Obesity

Insulin causes weight gain. This we know from numerous studies. Average insulin levels are twice as high as they were twenty years ago. As well as weight gain, insulin causes hunger and fatigue. Obese people have higher insulin levels than lean people.

What pushes up insulin? All foods cause insulin to rise but some more than others. As expected, the highest spikes in insulin occur with foods which increase sugar levels, such as sugar and refined carbohydrates. But some foods push up insulin independently of sugar. The most important of these are artificial sweeteners. Protein also increases insulin. Fat has the least effect. Basically insulin sets the thermostat and we need to find a way to bring this down.

However there is one more thing to consider and it makes a big difference. As we produce more insulin the body develops resistance to it, to protect us from its worst effects. This however is a two-edged sword. Once we develop insulin resistance we need even higher levels of insulin to process food and this makes us fatter still. The crucial point here is that the longer a person has been obese the higher their insulin resistance. This makes it much harder for a person who has been obese for decades to lose weight than someone who has been obese for months.

But what produces insulin resistance? The most important reason is persistent high insulin levels. Both persistent and high are key words here but some studies have found it is the persistent part of the equation that is the most important (see below).

But there is something else that increases insulin resistance. This is fructose. Sugar breaks down into glucose (blood sugar measures glucose) and fructose. Refined carbohydrates, bad as they are for our health, don’t contain fructose. There is a little fructose in fruits. Sugar is 50% fructose and there is more fructose (55%) in high-fructose corn syrup, used a sweetener in a multitude of processed food.

The problem with fructose is only the liver can break it down and it has a limited capacity to do this. The liver is our fail-safe mechanism when it comes to controlling sugar levels. When it is overloaded and we then have a surge of sugar this pushes up insulin levels even higher whilst simultaneously increasing insulin resistance. It is notable that fructose consumption has exactly paralleled obesity in the last few decades.

In one study subjects eating 1000 calories of fructose daily increased insulin resistance by 25% within 7 days, whereas 1000 calories of glucose had no effect. Another experiment found healthy volunteers who took 25% of their calories from fructose developed pre-diabetes within just 8 weeks. If we want to avoid obesity, fructose is enemy number one. And the main source is sugar and high fructose corn syrup.

But in terms of insulin resistance the other major trigger, as mentioned, is persistent high insulin levels. Obesity was rare in the 1970s. People ate three meals a day and didn’t snack much. After a meal insulin went up then it went down. At night insulin went down much more. As long as insulin fluctuates in this fashion we avoid the spectre of insulin resistance. Since the 1970s snacks between meals have become the norm and insulin resistance has been the inevitable result.

To sum up if we want to avoid obesity we need to avoid high insulin levels. All foods increase insulin but sugar and refined carbohydrates are the worst culprits. Sweeteners also substantially increase insulin.

It is also crucial to avoid insulin resistance, which unlike insulin tends to increase the longer we are obese. To avoid insulin resistance we need to avoid fructose in particular, so we need to avoid sugar and high fructose corn syrup. But because insulin resistance is related to persistently high insulin levels, the other major strategy is to have breaks between meals and the longer the better. In particular have a long break (ideally over 12 hours ideally) between the last food in the evening and the first meal the next day. Longer fasts are even more valuable. After 24 hrs of not eating the body has used up its glycogen reserves and starts to break down fat.

What Can I Do?

          The most crucial first step in dealing with obesity is to cut down on the sugars and refined carbohydrates.


          Many people think if they stop adding sugar to tea or cereals that they will be okay. Nothing could be further from the truth. Eighty per cent of food in the supermarkets contains added sugar and on average we eat 22 teaspoonfuls of sugar a day. World sugar consumption has trebled in 50 years.

The worst offenders are sugary drinks and fruit juices. A single cola drink can contain 10 teaspoonfuls of sugar, an energy drink 15 to 19 teaspoonfuls and commercial fruit juices 14 teaspoonfuls of sugar (freshly made fruit juices are usually much better).

A portion of pizza can have 8 teaspoonfuls sugar, most ready meals 5 to 10 teaspoonfuls of sugar, a packet of couscous 6 -10 teaspoonfuls of sugar, a can of baked beans 6 teaspoonfuls, a yoghurt 5 teaspoonfuls a portion of bran flakes 3 teaspoonfuls. sauces have between 1 to 3 teaspoonfuls per portion, even one sausage can have 1 teaspoonful of sugar. Nearly all low-fat products, cereals, soups, sauces, ready meals and processed foods contain lots of sugar.

The first step in dealing with sugar is simply recognizing it. Ordinary sugar is called sucrose; but sugar comes under many names: glucose, maltose, lactose, dextrose, molasses, corn syrup, palm syrup, rice syrup, polydextrose and hydrolysed starch. Though our bodies have hardly had time to adjust to so many sugars, we are now being exposed to novel sugars such as sugar alcohols, developed from the breaking down of starches, such as sorbitol, maltitol and mannitol. These can be converted by enzymes to maldextrins which are added to soft drinks and baby foods. Anything that ends in “ose” or “ol” is likely to be a sugar.

The best thing to do is to read the labels. Sugars are usually labelled per 100 grams. Anything above 4 grams (a teaspoon of sugar) per 100 grams means high sugar. You also need to reduce other refined carbohydrates such as white flour, white rice, chips, mashed potatoes and most cereal. These break down into glucose. In fact a useful rule regarding food is: if it’s white it’s not good for you.


Sugar and Fruit

          It’s not just the amount of sugar but the speed with which it is released. Faster release means more insulin and more fat storage. If you slow down the sugar absorption then it will be safe. A good example is fruit. Some fruits can contain quite a bit of sugar (especially dried fruits, bananas and tropical fruits) but also contain fibre which slows down the absorption (not so with fruit juice which will give you a sugar hit). However fruit is generally a healthy food. Fibre is one way of keeping insulin down which means eating unprocessed food such a fruit, vegetables and wholegrains. Fibre protects against obesity.

Artificial Sweeteners

          Artificial sweeteners all increase insulin. 83% of independent studies of sweetener have found they cause weight gain. In one study they increased obesity by 47%.  They have also been found to increase cardiovascular events.


Fats that make you Fat

A crucial study has helped us understand why we gain weight so easily today. In this ground-breaking study mice were fed either chow, (a rodent feed made from ground wheat with fish and animal products) 4% soybean oil or 19% soybean oil. All feeds had the same number of calories. Those fed 4% and 19% soybean oil developed 5.5% and 10% more weight gain respectively compared to those on chow. This was equivalent, in human terms, to gaining 190 pounds and a massive 294 pounds respectively in 36 weeks. What does this mean for us? It means that soybean oils (and other processed seed oils) are a major and usually overlooked cause of obesity.

Vegetable oils are everywhere; they make up 32% of the calories in the standard western diet (sugar 22%). Soybean oils were responsible for 0.02% of calories in 1909 but 20% by 2000. They cause 9% more weight gain than fructose (the sugar most responsible for weight gain). They have no nutritional value and a worrying number of harmful effects (weight gain, diabetes, heart disease, increased mortality). They are one of the most damaging foods we can eat. They are primarily found in processed foods and in industrially-produced cooking oils. One of the best things you can do for your health and your weight is to avoid processed foods (which virtually all contain these oils) and synthetic oils such as sunflower, soybean, safflower, rapeseed (also called canola) and corn oils. Cook in butter, lard (or good quality olive oil) instead.


Plate Size

          Plate size does matter as portion size has been gradually increasing over the last few decades so use smaller plates. Eat until only 80% full (this is typical of long-lived societies).

Fasting and Avoiding Snacks

The timing of food is as important as what we eat, and perhaps more important. Mice fed a high sugar diet put on large amounts of weight as we do, but those mice that ate exactly the same food but within an 8 hour time period but on far less weight. Studies on humans have found the same.

 Most fat burning starts about 6 hours after the last food of the day. The longer we can leave it after this the better, with an optimum result at 16 hours. Twelve hours is more realistic for most people but longer is better. It makes a real difference to sugar control if we can switch off insulin for as long as possible. So fasting, having long gaps between meals and avoiding snacks is critical to losing weight and to switching off insulin resistance. Ideally have at least 12 hours between the last meal in the evening and the first in the morning.

It is interesting that there have been half a dozen experiments to reduce obesity in children, mostly using the strategy of eat less, move more. All have failed spectacularly. But there was one successful intervention. It was the Australian Romp and Chomp study on children between 0 and 5 years old. This did 3 things: reduced sugary drinks reduced snacking and increased fruit and vegetables. This resulted in significant weight loss compared to controls. It is easy to see why this worked, once we understand insulin.

People worry about missing breakfast. They have been told it is the most important meal in the day. Recent research has found this is not to be true. The biggest problem with breakfast is that we are often in a hurry so we eat highly processed foods like bread and cereals which are the foods most likely to cause weight gain.



What about Exercise?

          Exercise went up in the UK between 1997 and 2008 but so did obesity. Numerous studies have found exercise doesn’t help with weight loss. Exercise is extremely beneficial for health but it help with weight loss. However although your weight might stay the same your body will have a different composition, you will have more muscle and less fat. Exercise builds muscle. Exercise also reduces the stress hormone cortisol which can aggravate weight gain.


What about your Mindset?

The mind has a powerful effect on the body. Many athletes know that visualizing success gives them a cutting edge on the sports field and have coaches to help them to achieve this. And yet many obese people see themselves as looking fat not only now but in the future. And this negative image is a major stumbling block to losing weight. But how do we change it?

First decide how much you want to weigh. Next decide what shape or measurements you wish to have. Create a clear picture of exactly how you want to look. Be as specific as you can. Believe you will attain it. Work out how much you would need to lose (at a rate of 2 to 4 lb a month) and how long it would take.

        Next see a compelling vivid picture of that new slimmer person as you look in the mirror. Do this every morning and evening and imagine it again before going to sleep and hold the image for at least a minute.

Healthy Eating

          It is difficult to gain weight on a healthy diet. The secret is not to go on diets but to introduce healthy eating into your life. The healthiest foods are the living foods. The four groups of living foods are fruit, vegetables, nuts (non-roasted and non-salted) and seeds. Unlike dieting, healthy eating will increase your energy and reduce your risk of many diseases.

        A variation on healthy eating is to simply have a fast with nothing but water or fruit and vegetable juice for one day once every week or even once a month. This is beneficial as it detoxifies the body and will also help weight loss.

Factory Farming

          Today 80% of animals are factory farmed. Animals are bred to put on weight as fast as possible and fed foods they would not normally eat to gain weight faster. This is almost certainly having an effect on our weight.

        Two studies, including the massive large EPIC-PANACEA, back up this conclusion. They found the meat which caused the greatest weight gain was chicken. Chickens are, of course, bred to put on weight at an incredibly rapid rate.

A related issue is that rats fed on GM food gained weight more rapidly than those given normal food. Today most factory-farmed animals are fed on grains including wheat, corn and soya to make then grow faster. Most corn and nearly all soya is genetically-modified. In this way, factory-farmed meat is likely to be adding to the obesity epidemic in two different ways. Wherever possible choose free-range, grass-fed, pasture-fed or organic produce, where animals are reared more naturally.

Food Intolerances

Occasionally I meet a patient who has tried every diet without success and even gains weight when they go on a very low calorie diet (say just fruit and vegetables). These patients often have many other symptoms (eg bloating & wind, fluctuating weight, fatigue, palpitations, sweating). They may be suffering from a food intolerance. They may need a drastic solution. This solution is to go on a fast of nothing put water for 5 days. Nearly always they feel markedly better despite not eating. The next step is testing foods one by one (see Food Intolerance leaflet). Often they will find some of these foods give them a sudden marked increase in weight (sometimes 7 to 14 pounds). Finding which foods they are intolerant can resolve the problem.

People who Eat lots of Food but Never Gain Weight

Some people seemed to eat lots of food and stay slim. Have they got a fast metabolism? Studies show this isn’t the case.But they do seem to have three strategies which help them. Even when sedentary they burn up energy and are typically active: fidgeting and moving about. Secondly they don’t snack. Thirdly after having big meals they seem to naturally eat less the next day, even if they don’t realize they are doing it. I think anyone can use these strategies to help lose weight.

Is Fat Dangerous?

Strictly speaking, fat on your body is not a health hazard it is only the fat around your organs (called visceral fat) that is dangerous. The best way to know if you have visceral fat is to measure your waist. If it’s too big (over 35 inches in women and 40 inches in men) then you probably will have visceral fat. However obesity does put you more at risk of diabetes (which has gone up in parallel with the obesity epidemic) and some forms of cancer.