Why We Eat (Too Much)
Highlights
Unfortunately, if you suck the fat cells out with liposuction (a common, short-term fix performed by plastic surgeons), more and more fat cells are produced to compensate.
The brain needs a constant level of glucose (sugar) in the blood to function. When there is no food readily available, this is replenished constantly by our fat cells.
fat is very clever, and very efficient, at self-regulation.
Most of the energy that we use does not involve any type of movement. If we were to lie in bed all day and all night we would still use up to 70 per cent of the energy that we normally do
over two thirds of our daily energy expenditure is not within our conscious control is an important one to grasp when understanding our metabolism – and how we control our weight and why some people develop obesity.
Any excess energy is stored first in the liver (as a type of sugar) and then in fat cells (as fat). The liver can only hold a couple of days’ worth of energy; it is generally full to capacity, so in practice excess energy is usually stored in fat.
The energy in fat can help keep us going for about thirty days without food. Knowing this takes us on to the rule that is almost always overlooked when explaining obesity.
This means that although the average American is consuming so much more than necessary, they regulate their energy balance to within 0.4 per cent of perfection. A separate validation study that more accurately measured energy usage over a year and weight gain found the system to be even more accurate, with only 0.2 per cent of calories ingested being stored as fat.
Because their metabolisms were so ‘hot’, they all lost their extra weight as early as twelve weeks after the experiment ended and they were able to resume normal eating. None of them needed any type of diet to get back to their normal pre-study weight.
Over-eating leads to the burning of energy through an increasing metabolic rate.
The Minnesota Starvation Experiment was the first study to prove that when you restrict a person’s calories, they will respond, or adapt, by reducing their BMR. Less energy in leads to less energy out.
Hunger is probably an even more powerful switch than metabolism when our bodies try and protect us from weight loss.
Although it appears that the amount we eat is under conscious control, in actual fact, it is our subconscious brain that controls our underlying hunger and eating behaviour. If the brain wants more energy on board, it will signal more hunger and less metabolic waste, and our weight will go up.
Invariably – but unfortunately for all dieters – biology always wins. It may take a week or a month or a year or even several years, but your subconscious brain will eventually haul your weight back to where it wants it to be.
Once we understand these signals, our weight set-point, and therefore our weight, will finally be under our control.
It is not the amount of food that will alter their weight set-point, it is the quality of the food. If a rodent is given high-calorie, high-fat foods (called ‘canteen food’ by the scientists), its weight set-point will be raised.1
The Western high street is like a food desert – natural foods only exist in rare, difficult to find, oases. The mirage of real food is around, but it doesn’t really exist.
This suggests that high-calorie availability will not affect weight, as long as those calories come from natural foods.
Obesity Risk is Three Quarters Inherited
if you have obese-sensitive genes, even a healthy home environment may not protect you.
when pregnant mice were over-fed with canteen-type food, their offspring exhibited increased appetite and aggressive food-seeking behaviour, and then became obese, in comparison to offspring of mice that were fed normally.
increasing levels of blood sugar in pregnant mothers predicts a much greater risk of childhood obesity,
maternal obesity during pregnancy predicts a two- to threefold increase in obesity of offspring by the time they reach four years of age.
when obesity is ‘cured’ by bariatric surgery (i.e. gastric bypass), the children that the mothers had after their weight loss showed no sign of epigenetic transmission of obesity traits, compared to their older brothers and sisters who had been in the womb when the mother was still obese.
First, we found that genes have a 75 per cent influence on a person’s weight (remember the study of twins). Now we are saying that if your mother happened to be obese at the time of her pregnancy, she would pass on to you not only her half of your genetic DNA code (which may predispose you to obesity anyway), but also mutations that favour obesity (because your genes were incubated within an obese body).
Despite a mother being over-weight, she may have vitamin, mineral or other deficiencies because the processed food she is consuming doesn’t contain the same nutrition as old-fashioned fresh foods (we discuss this further in chapter 8). The genes in the foetus sense the deficiencies in the mother and the genetic expression of those genes is thus altered to ensure that enough foods are consumed in the future environment to avoid a similar deficiency.
when you next see adolescents struggling with obesity. Not only are they having to cope with the normal teenage angst of growing up, but also with much stronger obesity traits than any previous generation.
If you happen to have the wrong genes in the wrong environment, then it is almost preordained that you are going to struggle with weight control – it’s not your fault.
If you try and fight against your weight set-point and consciously attempt to manipulate your weight downwards by dieting, you may, as the next chapter explains, make things even worse. The solution is to create your own personal environment, one that insulates you from those obesity triggers that your genes are looking for.
if you are struggling with obesity, in my experience the best solution (other than bariatric surgery) is to understand why your brain wants a high weight set-point. What signals is it receiving that makes it think it needs extra fat stores? These signals are the key to obesity and how to control it.
There is growing evidence that repeated weight loss and then weight regain – so-called weight-cycling or yo-yo-dieting are detrimental to future weight loss.
the mice that had gone through intermittent calorie-restriction diets ended up weighing more than the mice that had been eating a high-calorie diet throughout their lives. Dieting seemed to be counter-productive to weight regulation.
The brain cannot tell the difference between a diet that we go on from our own free will and a food shortage caused by an environmental catastrophe like a famine.
Recurrent dieting is a great way to train your body to become obese.
They are both overweight, but not obese, maybe dress size 12–14.
Our recurrent dieter is fighting against this losing battle by conscious calorie-counting and denying her appetite, while her body is responding with a lower metabolic rate.
The difference in metabolism in people of the same size is governed by whether their current weight is above, below or the same as the subconscious brain’s desired weight, i.e. their weight set-point. If you are heavier than your brain’s desired weight for you, then your metabolism will speed up; if your weight is below your set-point, as it is when you are a few weeks or months into a diet, your metabolism will slow down.
So if insulin is acting on the cell receptor, then there is no room within the cell to read the leptin signal as well, even if leptin is present and posting its message. The leptin message therefore goes unread.5 As a result, the hypothalamus thinks fat stores are low (when they are excessive) and stimulates appetite while at the same time cutting metabolic energy expenditure.
The profound effect that insulin has on leptin resistance means it too becomes critical in the control of our weight set-point.
Higher levels of insulin mean more leptin resistance and more leptin resistance means a higher weight set-point – and therefore a higher weight.
When the animals are put back onto their normal diet, their leptin resistance and insulin levels stabilize and their weight returns to normal levels.9
Unfortunately, our current Western diet predisposes us to high insulin levels.
When there is a combination of high insulin and lots of inflammation in the body, leptin will stop working. The leptin ➞ insulin ➞ inflammation interaction becomes a downward spiral once it gets started.
leptin resistance can be reversed by changing the quality of the food that is consumed.
it is impossible to sustain weight loss in the long term unless you have first reset your weight set-point to a lower level.
we can only do this by adjusting the type of food we eat, changing our food culture, de-stressing, improving our sleeping habits
If the signal is strong enough – if the sweet food is sweet enough – the signal we get, straight to our brain, is the same as if we had taken an opiate drug like morphine or heroin (maybe not a large dose – but the signal is the same). The sweetness signal calms our emotions and improves our mood.
The dwarf wheat that makes up the flour present in many of our foods today, from bread (white or brown – there is not much difference) to crackers and pasta, is so highly processed that within thirty minutes of us eating it, it has turned into pure sugar in our bloodstreams
If we measure sugar consumption per person since the 1820s (the golden age of healthy eating), there was a slow and inexorable rise over the next 100 years. In 1820, consumption was just 5lb per person per year; by 1920 this had increased to 80lb per year.
In the 1980s, after thirty years of consuming roughly the same amount of sugar each year, suddenly we started to consume more and more of it again. The price of sugar rose, doubling on average over this period, but this did not stop an inexorable rise in our sugar consumption: from 80lb per person each year in 1980 to 100lb in 2005.
However, the sugar industry had taken note of the shifting negative publicity and decided to act first. In 1967 they donated large sums of money to three prominent Harvard scientists who conducted research that exonerated sugar and shifted the blame for heart disease firmly onto fat.
showed no decrease in the rate of heart disease in people placed on low-fat diets. The only consistent result seemed to be a trend in the development of cancer among those subjects eating low fat.
Seeds from vegetable plants are heated to 180°C in a steam bath and compressed to help separate the oil. The oil is then put through another bath, not steam or water this time, but a bath made of the chemical hexane (the solvent glue sniffers are addicted to) and steamed again to help more oil to be extracted. The pulp is then put into centrifuges to spin the oil away from any remaining seed residue and phosphate is added. The crude oil is then separated, but needs further refining because it smells rancid at this stage. To produce a clear odour-free oil, processes known as bleaching and deodorizing are performed on the oil. Bleaching, as the name implies, requires the use of bleaching agents to remove impurities (such as chloroform) from the oil. The deodorizing process uses scorching hot (500°C) steam at high pressure to clean the oil
Trans-fats cause heart disease. In fact, they are very potent poisons that once in our bodies will increase those bad-cholesterol particles – the LDL type, small dense molecules that can burrow into your arteries, causing inflammation and atherosclerosis.
We had therefore come full circle in our quest to reduce heart disease risk. By lowering use of animal fats and increasing vegetable oils, we inadvertently increased trans-fats and increased our risk of heart disease. The detrimental effect of this change on heart disease in the population was masked epidemiologically for many years by the decrease in smoking rates and advances in the treatment of blood pressure.
So, how much trans-fat is too much? The new US Food and Drug Administration (FDA) guidelines state that intake should not exceed 1 per cent of total calories (20 calories or 2g/day). This amount can be found in a single serving of cake, biscuits or crackers.
Our expensive healthcare systems are fending off the diseases caused by the changes in our lifestyle. As a result, the life expectancy of a working-class man living in Britain in 2017 (seventy-three years) is the same as a working-class man (who had made it past the age of five years) living in the mid-Victorian era.11 Our medical advances have thus been nullified by our new ‘lifestyle diseases’ in terms of life expectancy.
the vast majority of wheat consumed was highly refined, and therefore had a similar effect on people’s insulin levels as table sugar.
Our brains and nerves are predominantly made up of fats; in fact the brain consists of 50 per cent cholesterol, so fat is essential for normal nerve and brain function.
The omega fats are unique: we are unable to make these fats ourselves. Just as for vitamins, we are reliant on eating foods that contain them. They are therefore known as essential fatty acids – because it is vital to our wellbeing that they are part of our diet.
Chloroplasts produce omega-3.
omega-3 is the most common fat in the world. You would never have thought that a serving of spinach or lettuce contains a fat that is so abundant, and so essential to our health.
any animal or fish that ingests green plant matter will therefore also contain omega-3
Omega-6, the other essential fatty acid, is also made by plants, but it appears in their seeds and not in their green leaves.
The vegetable oils that replaced saturated fat are made from seeds and therefore contain abundant omega-6.
As the amount of omega-6 in our diets has skyrocketed, so, as expected, has the amount of omega-6 that we carry in our tissues.
Levels have gone from 8 per cent – matching other primates (chimps) in 1961 – in a slow progressive rise as more and more vegetable oils and grains have been consumed, to 23 per cent in 2008.
More intensive farming methods mean that most cattle are now fed grains to make them grow faster
Grain-fed cattle take in the large doses of omega-6 from the grains and miss out on the omega-3 that they would normally obtain from grass.
If It Has a Shelf Life, It Doesn’t Contain Omega-3
Ideally, and throughout our history, the ratio of omega-3 to omega-6 within our bodies would have been between 1:1 and 1:4
So, the omega-3 to omega-6 ratio rises to a staggering 1:50 in some Westernized cities.
affinity. The more omega-6 in the cell wall, the more the appetite and weight-regulating system will be ratcheted towards weight gain.
high levels of omega-6 can prevent the body from converting the omega-3 that we get from plants to the more active omega-3 that we get from fish and animals.
So we have a compelling argument that, yes, a deficiency of an essential dietary nutrient – omega-3 – is a cause of obesity.
the omega-6 to omega-3 ratio takes months to change, and dieting will not have an impact on this.
the altered omega fatty-acid ratio in the Western diet causes a raised weight set-point. Hunger and tiredness are then the symptoms of the condition and result in weight gain and, ultimately, the disease of obesity.
Increased cellular omega-6 levels cause an increase in inflammation (contributing to a range of Western diseases). Increased inflammation (via TNF-alpha) leads to poorer functioning of insulin and a dulling of the effect of leptin (the hormone produced by fat cells that keeps us thin). Poorer insulin function means that more insulin is required within the blood. Higher levels of insulin also result in a dulling of the leptin signal. All these effects result in a rise in the weight set-point and then, inevitably … weight gain.
If insulin levels in our bloodstream are high, then we can expect that our weight set-point will be raised.
There are many scientific studies that confirm that altering insulin levels will lead to changes in body weight. Increase insulin and you will increase weight; decrease insulin and you will lose weight. Insulin changes the set-point – up or down – and then the weight will follow.
We have large reserves of sugar stored in our muscles and our liver, but only one teaspoonful is present in the whole 5 litres of our blood. Our glucose-transporting hormones, particularly insulin, are essential in maintaining this level of glucose in our blood to keep us alive and healthy.
the amount of glucose being dumped into our blood, and the speed at which it is being dumped, depend on what we have eaten. Therefore insulin levels are directly influenced by the type of food that we eat.
if that food has a tremendous amount of sugar in it, then it will cause a violent spike in insulin secretion. The large surge in glucose entering the bloodstream is followed by a large surge in insulin. The insulin works to open up the fat cells to suck the sugar into them but … here is the catch: because of the insulin surge, too much glucose leaves the bloodstream, leading to the blood-sugar level falling. This sets off alarm bells in the brain which is dependent on glucose to function. The alarm gives us a feeling of anxiety and a very strong craving for any food containing sugar. The brain is stepping into critical survival mode – ‘Get sugar and get sugar fast!’ is the message.
The cumulative effect of the sugar roller coaster is that we consume much more glucose, much more sugar, than we would normally crave from a healthy balanced diet. By eating so much highly processed food, and with the new culture of satisfying ourselves during the day on snacks, we are increasing the total amount of insulin that is required to cope with these waves of glucose. As we know, the total amount of insulin that we use is reflected in our weight set-point. Higher than average insulin levels over several weeks will increase your set-point, and weight gain will follow.
Whereas lower than average insulin levels over several weeks will lower your set-point and effortless weight loss will follow.
Once we decrease our average insulin level, our weight set-point, and then our weight, will fall.
When we consume fat, it triggers a strong release of the satiety hormones
When you eat the correct foods, avoid snacking and enjoy and embrace a lower stress life, there is no need to count calories – your set-point will be within a healthy range and your metabolism will keep it there.
OK, so now you have decided not to go on a diet, but instead to cook better-quality food and exercise a couple of times a week. Note here that there is no calorie-counting involved in this change. You are just altering a couple of habits for the better. The outcome would be – no dramatic weight loss; probably no weight loss for weeks or months
However, if you continued with your better dietary and exercise habits, eventually the message would get through to your weight set-point after some months. Your set-point would go down and maybe many months
later you would be 4.5kg (10lb) lighter. A year down the line your weight might settle at 10kg (22lb) lighter. But, unlike the weight loss through dieting, your body would be happy with this weight loss. Your actual weight would be matching your weight set-point,
weight set-point. Weight loss by changing your habits and environment (e.g. walking to work, doing a sports class or going to the gym a couple of times a week), and therefore changing the signals that you are sending to your weight-control centre, is the only way to successful, sustained weight loss.
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.
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.
The best way to be sure that you are eating food that is good for you is to buy fresh ingredients and cook them.
If you are unduly stressed, then your metabolism acts like that of an injured animal – the cortisol message means you’re not going to let go of energy stores easily.
Remember, if all else fails, sleep, exercise, music, massage, dancing and laughter all help to lower cortisol levels.