Why we eat too much – the new science of appetite by Dr Andrew Jenkinson - book review

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[DATE OF FIRST PUBLICATION OF THIS PAGE - DECEMBER 2023]

.... with added comments from yours truly

Obese Roman Gladiators

[By Craig]
Some Roman gladiators were overweight vegetarians and not the muscle-bound men portrayed by actors like Russell Crowe (My Name Is Maximus | Gladiator (2000)). Austrian scientists analysed the skeletons of two different types of gladiators, the myrmillos [armed with a gladius - short sword - and scutum - rectangular shield] and retiariae [armed with a rete - weighted net - and a tridens - three pointed trident], found at the ancient site of Ephesus, near Selsuk in Turkey. These men* ate mainly (very large quantities of) barley and dried fruit. Barley is a grain with a ratio of Omega 6 to Omega 3 of around 9 - see section 13 below. Dried fruit raises insulin - see section 8 below.

Note * Some gladiators were women. At one stage, female warriors regularly fought against dwarves as well as other women. However, Septimius Severus outlawed their involvement around 200 AD.

In the [very!] short term, this diet gave these gladiators strength but they were fat.

See Dying in the arena: the osseous evidence from Ephesian gladiators

Indeed, obesity in Rome was once considered a form of entertainment and some emperors were fond of keeping a glutton [ a gulosus]. These gulosi were fed, yes you guessed it, barley and dried fruit.

The Romans knew how to make people fat!

Amazon links for “Why we eat too much – the new science of appetite”

See

Introduction

It is not a case of calories in equals weight gain as evidenced by decades of calorie restriction diets. Not only do they fail but they encourage long term weight gain. Calorie restricted dieters end up fatter than they were before they started. Andrew Jenkinson looks at the science.

Our weight "thermostat"

We all have a “thermostat” for weight - a “set point” which is controlled by genetic and environmental factors. If we eat more than we need then the body burns it off through increasing basal metabolic rate. If we eat less than we need, we become cold, lethargic and depressed and hormones are released to stimulate appetite so we eat more. An understanding of how the body does this gives us vital clues to help the overweight.

Factors affecting our weight

Genetic factors:

Being over weight runs in families. The fattest people in the world are the South Pacific islanders. Jenkinson argues that it was only the genetically obese that survived the long sea voyages from other countries to colonise these islanders……and their genes survive to make these people the fatties of the world.

Epigenetic factors:

The Dutch famine occurred during the winter of 1944 when they were starved by the occupying German army. Some pregnant women starved. Their offspring were characterised by a tendency to obesity. Whilst in the womb they had been starved and the body compensated for life with a high “thermostat” for weight. Calorie restricted dieting has the same effect. One can lose weight through starvation BUT low leptin means the metabolic rate reduces (so you feel cold, fatigued and depressed) AND the high ghrelin and peptide YY stimulates appetite so you feel permanently hungry. The brain can think of nothing but the next meal! The subconscious brain thinks there is a famine and resets the weight thermostat higher to deal with the next “famine”. The overall result is weight gain. 

DO NOT DO CALORIE RESTRICED DIETING = IT MAKES THINGS WORSE.

How appetite and satiety is regulated

We do this through several hormones-

The hormones What they do The effects How to mitigate
Leptin This is produced by fat cells in the body.Leptin reduces the appetite So the more fat cells you have, the less you crave food (this works well until insulin gets in the way! Read on!) Reduce carbohydrates
High leptin stimulates growth and reproduction AND increases the basal metabolic rate When we have high leptin. this is a signal to the body that it has the reserves for reproduction
Famine causes low leptin In a famine we shut down basal metabolic rate to conserve energy. We hibernate – we become fatigued, cold, foggy, depressed and fat Do not calorie restrict! It makes us fatigued, cold, foggy, depressed and fat!
Ghrelin This is produced in the upper part of the stomach in response to food No food – lots of ghrelin – appetite is stimulated. With food – ghrelin is switched off so appetite declines and we feel satisfied by that meal Eat slowly, chew food, to give the hormones time to impact
Peptide YY This is produced in the small intestine and is stimulated by protein A high protein diet reduces appetite (so you eat less to achieve protein satiety). A low protein diet increases appetite (so you eat more to achieve protein satiety). This is called ”protein leverage”. We need normal amounts of protein for normal weight. A low protein diet and your “thermostat” for weight will increase so you will gain weight Eat the “right” amount of protein (see PK cookbook). For me at 61kgs, age 65, daily calories 1,843 I need 83 grams protein which is about 2 eggs, one pork chop, tin of sardines. See section 3.4 of Diet - what you need to eat to slow the normal ageing process
Thermogenin Present on mitochondria – this switches on fat burning to generate heat. This brown fat is vital for babies at birth to keep warm. You can switch this on by long term exposure to extreme cold – but this is far too uncomfortable for me! Yes, I am a wimp! Cold water swimming. CFS and ME sufferers please see Exercise - the right sort in Chronic Fatigue Syndrome
Sarcolipin Present in mitochondria Makes muscle cells burn glucose to generate heat.Allows one to burn off excess calories consumed See Exercise - the right sort
This is switched on by the sympathetic nervous system and is part of the flight or fight reaction Competitive sports – this is a “good” sort of stress! CFS and ME sufferers please see Exercise - the right sort in Chronic Fatigue Syndrome
Insulin Raises the set point for the thermostat for fat stores High insulin and we gain weight. This occurs naturally in the autumn when a carbohydrate windfall makes us fat to survive the winter. The problem now is we have a carbohydrate windfall all year round! PK diet - see The Paleo Ketogenic Diet - this is a diet which we all should follow and My book - Paleo-Ketogenic: The Why and The How
Causes leptin resistance So we crave food, shut down BMR and hibernate

When things go wrong

The mystery is that people who are overweight have high levels of leptin – you would think that would switch off the appetite so weight could be lost easily, and stay off. The answer is that there is leptin resistance.
Leptin resistance means you crave food, the metabolic rate is slowed and the weight piles on. Polycystic ovaries may also result.

What causes leptin resistance?

High levels result from How to combat
Insulin High carbohydrate diets

Sugar is the worst offender. The body contains about 5 litres of blood and for a normal blood sugar this contains about one teaspoonful of sugar (5 grams). Very little sugar is needed to spike blood sugar and insulin!

No sugar, fruit sugar or honey. Avoid artificial sweeteners (the brain is intelligent - -if it detects something sweet in the mouth then it will pour out insulin in anticipation of a sugar rush
The amount of insulin produced is proportionate to the rate at which the blood sugar rises. Avoid sweet alcoholic drinks (the alcohol acts as a solvent so sugar levels in the blood rise quickly - beer is the only substance with a glycaemic index higher than sugar). Eat slowly – do not gobble food. Eat a low carbohydrate, low GI foods. With the meal on your plate, eat the salad and green veg first, then the protein …… before starches. See The Paleo Ketogenic Diet - this is a diet which we all should follow and My book - Paleo-Ketogenic: The Why and The How
TNF alpha This controls the amount of inflammation in the body. It is produced by fat cells. TNF alpha causes insulin resistance so the pancreas pushes out more insulin and that causes more leptin resistance Western diets high in carbs, processed foods and omega 6 fatty acids increase TNF alpha
Pregnancy (making diabetes more likely in pregnancy) Avoid female sex hormones which produce a hormonal environment similar to pregnancy

A brief history of humans, hunting, food and cooking

Humans have the largest brains of all mammals. But the brain is an expensive commodity- - it uses huge amounts of energy and must be supplied with such. But brains gave us the ability to hunt and to cook – both greatly increased their ability to access nourishing foods. This is the “expensive tissue hypothesis”!

Humans are persistence hunters – they run down their prey. They know this and are clever enough to just keep running, they are hairless so they can keep cool by sweating (their prey pants to lose heat and this demands more energy) and the human arms are freed up to throw stones and spears.

Brains also gave us the ability to use fire to cook. We have cooked for one million years. This allowed us to get many more calories from food. It explains why we have a small gut (compared to other apes), smaller jaws and teeth (because cooking tenderises and tools allowed us to smash open bones for the highly nutritious bone marrow). Offal was the prized food because of its high fat content muscle meat is 15% fat, heart is 25%, liver 30%, brain 50% and bone marrow 84% fat!

By contrast, a study done on 500 people eating raw food diets (raw meat, raw fish, olive oil, nuts seeds, salad, veg etc) resulted in massive weight loss of 10kgs in women 12kgs in men. Over 30% had severe fatigue and periods stopped in 50% of the women. This is because our small human gut could not cope with raw food and so leptin levels ran low.

Brains allowed us to grow agricultural crops and this started in Egypt 20,000 years ago.

The early 1800s, the Victorian age, was a nutritional golden era. If you survived to age 5 (appalling sanitation and dirty water made for infectious disease) life expectancy was over 80 years. Why? People consumed offal, fish, lots of vegetables and fruit in season. Problems arose when sugar became abundant and cheap. Initially it was just a flavour enhancer but then its addictive nature cut in so that by the 1980s Westerners were consuming 75lbs a year rising to 100lbs per year on 2000 and 115lbs per year in 2020. This has been paralleled by obesity rates – why? Because insulin drives leptin resistance which drives hunger. The more sugar we eat the hungrier, colder and more fatigued we become.

Obesity as a deficiency disease?

With the nonsensical hypotheses that fatty food, especially saturated fats, make you fat, we have to look at how the food industry responded. It did three things:

  • It replaced saturated fats with vegetable oils (such as soyabean, sunflower, safflower, rapeseed etc) – actually the average total fat consumed increased by 240kcals per day
  • Increased grain consumption – actually the average total grains consumed increased by 170kcals per day
  • So we consumed many more processed foods daily (a combination of the above).

Processed foods need to be stable so they last for months in packets. Omega 3 oils are not stable - -they go off quickly (they go rancid). So all vegetable oils are treated to get rid of the omega 3. This is achieved by heat treatment or hydrogenation which generate the cardio-toxic trans fats

In consuming so much vegetable oils we greatly increased our consumption of omega 6 oils and much reduced consumption of omega 3 oils. Does this matter? Yes! Because omega 6 (see above) stimulates the body’s production of TNF alpha which causes insulin resistance so the pancreas pushes out more insulin and that causes more leptin resistance. We get fat!

Omega 3 fat is the sunshine fat

This is rich in green chloroplasts (which create energy from sunshine) and are so rich in animals which consume greenery. We should consume grass fed beef and lamb together with seafood (which ultimately gets its food from green plankton). Mitochondria in animals are very similar to chloroplasts in plants – omega 3 is vital for mitochondrial health and so energy.

Omega 6 fat is the autumn fat

Omega 6 comes from grains, seeds and nuts – the autumn harvest. In a trial when humans were fed safflower oil and margarine, death rates from heart disease increased (compared to those eating saturated fats and animal meats and butter). Furthermore animals (beef and pork), birds (chickens, turkey, ducks) and fish (fish farms) are fattened on grains – which are rich in omega 6 fats. Farmers do this because these animals, birds and fish grow and get fatter quicker on grains! What creates those fat, farmed, foods make us humans fat too. As a result the percentage of omega 6 in our body fat has increased from 8% (that of wild chimps) to 23% by 2008, and doubtless still rising. These omega 6 foods should only be available in the autumn, to make us fat in preparation for the winter. But we eat them throughout the year on a daily basis.

Worse, vegetable oils are highly processed by:

  • Seeds heated to 180degress centrigrade for oil extraction
  • Hexane solvent is used to enhance extraction
  • Bleaching
  • De-odorising at 500degress centigrade

And all these processes create the toxic trans fats.

Obesity is driven by too much omega 6 and too little omega 3

Yes! Obesity is a deficiency disease! The proportion of omega 6:3 in the diet parallels obesity rates

Country / People Proportion of omega 6 :3 Prevalence of obesity Reference
Palaeolithic tribes 0.79 Virtually zero
Japan 4 Less than 5% Obesity Rates by Country 2023
UK and Europe 15 25% Obesity Rates by Country 2023
United States 16.74 35% Obesity Rates by Country 2023
Urban India 38-54 Up to 40.6% Wikipedia Article - Obesity in India

High ratio of omega 6 to 3 causes insulin resistance and so leptin resistance to encourage obesity, inflammation, and fatigue………….and there is a final twist – high levels of omega 6 inhibit the body from converting the raw material omega 3 (in green plants) to the active downstream omega 3 molecules (from meat and fish).

The mechanisms by which Omega 6 and omega 3 impact on obesity

These fats concentrate in cell membranes and control cell defence, cell wall permeability and cell messaging -

Factor Omega 6 effects Omega 3 effects
Cell defence (inflammation) Increase inflammation. Increase blood stickiness increasing risk of blood clots: arterial disease, strokes, heart attacks, pulmonary embolus Decrease inflammation. Decrease blood stickiness
Makes the immune system more sensitive increasing risk of allergy and autoimmunity Less risk of allergy and autoimmunity
Increases TNF alpha that causes insulin resistance so the pancreas pushes out more insulin and that causes more leptin resistance and so obesity results Protective against obesity
Cell wall permeability (insulin) Makes cell membranes stiffer…… Makes cell membranes more fluid and adaptable so it can move minerals such as calcium, magnesium, sodium and potassium efficiently….
……….so they do not respond as well to hormones such as insulin.Insulin resistance (the basis of type 2 diabetes) results ….so cells are more sensitive to signalling molecules such as insulin (in the muscles) and leptin (in the brain)
Messaging (mood and appetite) Stimulate our endocannabinoid system which:

Increase appetite and calorie intake
Enhance the sweet taste of food, and increases the dopamine “reward” of food
The above two result in obesity.This is not an issue if you are eating PK!

In the brain low omega 3 associated with dementia, multiple sclerosis, anxiety, mood disorders, suicide.
With age, stress and inflammation out endocannabinoid system fails. This is why CBD oil has many uses!

See:

Other interventions to tackle obesity

What? Why? Action
Stress Our response to stress is to produce cortisol and this increases the set point “thermostat” for fat. We need energy to deal with stress so we crave carbs - -but if these are not “burned off” by physical exercise (the usual way primitive woman dealt with stressful demands) we get fat. Reduce stress – easier said than done!
Sleep Lack of sleep is stressful so cortisol is raised AND we use addictions, including carbs, to mitigate the unpleasant short term symptoms of stress. This is called comfort eating Get the best quality sleep possible. See Sleep is vital for good health - especially in CFS
Female sex hormones Encourage weight gain to prepare for the energetic demands of pregnancy breast feeding and child rearing Avoid the Pill and HRT. See The serious complications of taking the Pill and HRT
Microbiome We know this impacts on weight but the mechanism is not known. We do know that the greater the diversity of the gut flora, the healthier you are. Aim to consume at least 30 different foods per week. People consuming a carnivore diet have a diverse microbiome
Eat organic. 54% of the microbiome is sensitive to glyphosate, the most used pesticide in agriculture. Reference - Impact of glyphosate (RoundupTM) on the composition and functionality of the gut microbiome
Exercise Anaerobic exercise increases muscle fibre and raises BMR See Exercise - the right sort
Aerobic exercise is fun and reduces stress Choose something that you enjoy or this will not be sustainable! For me this is gardening, dog walking and riding (yes - I am a lucky sod and I know it)

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