The Obesity Epidemic: What Caused It? How Can We Stop It?

by Zoe Harcombe

2) The Krebs Cycle (which was discovered by Hans Adolf Krebs in 1937 and is also known as the citric acid cycle) – this takes place in the mitochondria (the mitochondria are the main sites of energy production in a cell) and has two goals a) to convert pyruvate into Acetyl CoA and b) to perform the full operation of the Krebs cycle – i.e. to produce 2ATP’s, 8NADH’s (NAD stands for Nicotinamide Adenine Dinucleotide and is a coenzyme found in all living cells), 2 FADH2’s (FAD stands for Flavin Adenine Dinucleotide and is a coenzyme involved in several important reactions in metabolism.

3) Electronic Transport Phosphorylation (also known as chemiosmosis) – this takes place in the mitochondria and the goal of this end part of the process is to break down NADH and FADH2, generating the major part of the ATP production in the whole three stage process.

If oxygen is not available (the body is in a state of anaerobic respiration), pyruvate is converted to ethanol or lactate and energy can be produced for a limited period of time with lactic acid being an unpleasant side effect. If oxygen is available, the two molecules of pyruvate enter the Krebs cycle. The first step in the process is the conversion of pyruvate into a form that can enter the citric acid cycle. For this to happen, pyruvate loses one carbon, as carbon dioxide, to form acetyl coenzyme A (Acetyl-CoA being the start of the cholesterol production process). Acetyl-CoA is effectively an activated form of acetic acid (vinegar). It is Acetyl-CoA that enters the citric acid cycle.

The conversion from carbohydrates into ATP requires B vitamins. Hence the argument that sugar provides energy is not strictly true. The body needs B vitamins from elsewhere to enable sucrose to be converted into usable energy. This is why sugar/sucrose has been called an anti-nutrient, as it depletes the body of vitamins from other food sources in its metabolism.

We also know from glycaemic index studies that cooking foods and processing foods increases their glycaemic index, so cooked carrots have a higher glycaemic index (33 to 85) than raw carrots (16 to 30).

The GI of fructose is low because fructose can only be metabolised by the liver and so most of the fructose consumed goes straight from the small intestine to the liver. The single biggest dietary change that human beings have endured during the past 100 years is not just the increase in sucrose, but, specifically the increase in fructose.

It is the modern ingestion of carbohydrate, in the form of sucrose and HFCS, which has so dramatically increased fructose intake, as this comprises fructose and glucose and not just glucose.

Respiratory Quotient for alcohol and different sugars and used this ratio to inform us about the metabolism of these substances by the body. (The Respiratory Quotient is the ratio of the volume of carbon dioxide expired to the volume of oxygen consumed by an organism or cell in a given period of time). The Respiratory Quotient for carbohydrate is 1.0; the RQ for fat is 0.7 and various figures are given for protein between 0.8 and 0.9. If the Respiratory Quotient goes above 1.0, this indicates that anaerobic (without oxygen) respiration is taking place. Under anaerobic conditions the cell cannot operate the citric acid cycle and the subsequent electron transport chain because both of these processes depend on oxygen. In this circumstance ATP can be generated with lactic acid fermentation – hence the burn that anaerobic exercise can generate.

we know fructose is the sugar driving the observed higher Respiratory Quotient. The Respiratory Quotient for the human subjects, following the consumption of fructose or sucrose, was regularly above 1.0 during Higgins’ experiments. This meant that the person had entered a state of anaerobic respiration (no exercise was being undertaken). The conclusion reached was that the body could not metabolise the fructose or sucrose quickly enough to use it as energy and therefore it was concluded that fructose/levulose is more easily converted to fat by reason of its respiratory quotient being so often above 1.0.

Shafrir noted that fructose places a metabolic load on the liver, which responds by converting it into triglycerides (fat) and then dispatching this in lipoproteins out from the liver around the body.[271] The title of the conference that I attended, Fructose – the lipogenic carbohydrate derives from this fact. Glucose entering the blood stream has the chance of being used for energy before being turned into glycogen and stored in the liver. Fructose goes straight to the liver to be stored.

the metabolic effects of fructose are due to its rapid utilisation by the liver and it by-passing a key step in glycolysis, leading to “far reaching consequences to carbohydrate and lipid metabolism”.

Lustig concludes that “fructose is a poison” and presents a compelling case for this, accusing fructose of causing metabolic syndrome (obesity, type 2 diabetes, lipid conditions, hypertension and cardiovascular disease). He also notes an interesting role played by fructose in obesity – that it does not suppress grehlin, the hunger hormone and it does not stimulate insulin, or leptin, the latter being the signal to the brain that something has been eaten.

The final point to make on why fructose is increasingly being called the fattening carbohydrate is that it is more efficiently converted into glycerol than is glucose.

The combined potency of sucrose/high fructose corn syrup is as follows – as the fructose proportion heads to the liver for its metabolism it has little impact on blood glucose levels. The glucose proportion performs this role and stimulates the pancreas to provide insulin. Hence we have triglycerides being formed, courtesy of the fructose, and they are able to be stored, thanks to the glucose causing insulin to be provided. Food manufacturers may like to argue that all sugar is equal – but, when it comes to enabling fat to be stored, the glucose/fructose combinations are more equal than others.

100 grams of olives delivers the equivalent of 20 micrograms of retinol (assuming that the body is capable of converting carotenes to retinol). Lamb’s liver delivers 7,392 micrograms of retinol per 100 grams. That means we would need to eat three kilograms of olives (4,350 calories) or eight grams of lamb’s liver (11 calories) to meet the recommended dietary allowance of vitamin A.

Guavas and peppers provide the highest single source of vitamin C from fruits and vegetables respectively – with 228 milligrams per 100 grams for guavas and 183 milligrams per 100 grams for raw yellow peppers.

The more commonly consumed fruits don’t compare quite so favourably with, say, the 43 milligrams of vitamin C per 100 grams of chestnuts: apples have 4.6 milligrams per 100 grams and bananas 8.7 milligrams per 100 grams. So, we don’t even need fruits and vegetables for vitamin C, although they can be good sources of this vitamin.

the best sources of calcium are dairy products and tinned fish; egg yolks, beef, cheese and liver are the best source of chromium; iron is best provided by organ meats; iodine is found in abundance in fish and kelp (seaweed); magnesium and manganese are plentiful in nuts and whole grains; good sources of selenium are organ meats, fish and shellfish and zinc is found in oysters, liver, meat, cheese and fish generally. Potassium is the one mineral for which fruits and vegetables are the best sources. Potassium, however, can also be found in all of nature’s foods, so we don’t need fruits and vegetables to obtain this mineral.

The best providers of the essential macronutrients are animal foods – meat, fish, eggs and dairy. The best providers of vitamins and minerals are animal foods again, with seeds and a few non animal foods (kelp and peppers) being useful. The most nutritious foods on the planet, therefore, are animal foods.

we need to avoid the processed foods themselves and not any real foods that may happen to be within them.

get the RDAs from just five foods. This can be achieved with 100 grams of liver, 200 grams of sardines, 200 grams of whole milk, 100 grams of sunflower seeds and 200 grams of broccoli (1,300 calories).

500 grams of whole milk, 450 grams of eggs (10 medium eggs), 300 grams of spinach, 250 grams of raw mushrooms grown in sunshine and 50 grams of sunflower seeds (1,360 calories).

One of the problems of trying to pick just five foods is that we end up with many vitaminsand minerals over, or under, represented in our diet. We should consume a wide variety of nature’s food.

When we get hungry after exercise, as we undoubtedly will, we have to ignore that most basic of human drives – the urge to eat – and ensure that energy goes out, but not in.

We also need to be able to explain how the emergence of obesity in babies (six months old) can be explained by sedentary behaviour, despite the fact that they have no means of controlling their energy out.

Had people consumed the same number of calories in the form of zero carbohydrate foods, they would have been unable to store fat and therefore would not have gained weight regardless of activity levels.

we note at the outset that exercise is only claimed to have a medium level of evidence for moderate preventative and therapeutic benefits for obesity.

It seems far more plausible that carbohydrate consumption, especially processed carbohydrate, is a root cause of overweight and insulin resistance and other serious metabolic consequences, rather than sloth. Human beings have as naturally evolved to avoid expending energy as they have evolved to gathering energy. I do believe that inactivity plays a part in the vicious cycle, but not that it is the root cause. The ‘but for’ test for me comes down to modern processed food. This is the thing that has changed so dramatically during the time of the emergence of the obesity epidemic. Inactivity is a consequence of our current poor nutrition providing no useful energy for the mitochondria and a consequence of the overweight being less able to move and that’s the downwards spiral.

Unfortunately, few reliable data are available on the relative contributions to this obesity epidemic by energy intake and energy expenditure, although both as well as individual variation are important. While more information is gathered on the varied causes of obesity,

The obesity epidemic has been thirty years in the making. If we can’t make a compelling case for the role of exercise by now, is it reasonable to suggest that is because there isn’t one? If a comprehensive report, with 84 references, written by two organisations which, it would be fair to say, are likely to have a positive view of the benefits of exercise, can only find that the data “are not particularly compelling”, perhaps it is time to look at the problem in a different way.

The researchers found that the predicted and actual weight gain matched exactly in children, leading them to conclude that the increases in energy intake alone explained the weight increase during the period in question. “For adults, we predicted that they would be 10.8 kg heavier, but in fact they were 8.6 kg heavier. That suggests that excess food intake still explains the weight gain, but that there may have been increases in physical activity over the 30 years that have blunted what would otherwise have been a higher weight gain,”

expectations regarding what can be achieved with exercise need to be lowered and public health policy shifted more toward encouraging people to eat less.

The final observation that we would need to be able to explain, if sedentary behaviour were the cause of obesity, is the emergence of obesity in babies (six months old).

If a baby is unfortunate enough not to be breastfed, the infant can be started on a diet of 60% sugar from the first moment something is put in its mouth.

With the top two ingredients being wheat flour and sugar, we are indeed introducing baby early on to the two main ingredients it will consume for the rest of its ‘plate or pyramid’ life.

Heinz fed babies can also enjoy delights such as banana and chocolate dessert: “a taste sensation”, “delicious tasty strawberry cheesecake” and even “scrumptious” mild sweet chilli with chicken sauce – all with added sugar. I’ve got my own view on the cause of obesity in six month old toddlers and it has nothing to do with sedentary behaviour.

TV arrived in the 1960’s, obesity took an upwards turn around 1980 (yes, when we changed our diet advice).

we were watching the same number of hours of television in 1992 and yet obesity has gone up dramatically since this date.

I suggest that it is not watching television per se that is a cause of obesity, but rather the snacks that we eat while watching television that cause obesity. Someone simply watching three to four hours of television in the evening and eating nothing during this time can only store as fat what they ate that day. Fat storage depends on carbohydrate and insulin. It cannot be caused by watching television.

Jogging only needs twice as many calories as moderate housework and the latter can be sustained for much longer.

over time fewer men and women reported no leisure-time physical activity”

“The percent of the labor force in high activity occupations remained steady from 1950 to 1990 at around 16% to 17%.” So, during the period when obesity increased from under 5% to over 20%, the proportion of people in high activity occupations remained steady.

the connection between poverty and obesity. If having access to TV, not working manually and being able to afford labour saving devices were the cause of obesity, there would be a positive correlation between income/socio-economic group and obesity. The richer the person or family, the more inactive and obese they would be. In fact the exact opposite is true. There is a strong correlation between low income and high obesity.

“The prevalence of obesity was 7 times higher among women reared in the lowest social class category as compared with those reared in the highest category.”

Lower income individuals and families have less access to cars, more reliance upon public transport, fewer energy saving devices and they tend to be concentrated in manual labour occupations. The majority of roles in catering, cleaning and construction, as just three examples, are poorly paid and highly physically demanding. A coffee shop barista is on his or her feet all day long, for little more than minimum wage. Builders are the modern day equivalent of mine workers and the company owners tend to be the rich and inactive and the manual workers tend to be the poor and active. Builders are so notoriously overweight that cartoons and situation comedies feature ‘the builder’s bum’ –

What does explain the correlation between poverty and obesity is food intake. Not the quantity (I haven’t fallen for the energy in notion), but the type of food eaten. If

Poor people eat poorly; it’s a sad indictment of modern life.

The more affluent shoppers are throwing cherries in the trolley without looking at the price. The lower income parents, with a family to feed, are trying to get the most food for the least money and this all too often ends up being manufactured, processed, nutritionally lacking ‘junk’.

One of the most compelling arguments for me, against exercise being the key to the obesity epidemic, is the simple fact that we can eat in one minute enough fuel for one hour. The relative importance of not eating something vs. eating it and trying to use the fuel, is enormously weighted towards not eating something in the first place. This is not a new concept. Newburgh (1942) noted that a man can climb a flight of stairs or forego one quarter teaspoon of sugar.

The apple group needed to run for 13 minutes, the crisp group needed to run for 42 minutes and the confectionery group needed to run for one hour and five minutes to burn off their item.