(This spell of posts stems from our desire to make you familiar with the origin of some of the mainstream disease conditions and point out that only flawed food can play a partial role in causing them; smart food can actually help keep them at bay. Do read and re-read them; you will be rewarded with very useful info. After the first 4 obesity posts, we dive straight into the disease that is closest to our heart – the Coronary Arterial Disease.)

We are dedicating 4 consecutive posts to obesity because…….

1. It is rampant in developed economies (where even children fall prey) and not-so-rare in developing ones. It forms a diabolical triad with cardiovascular disease and diabetes – all interrelated – while also being a factor in other pathologies.
2. It is more ‘multi-factorial’ than most chronic conditions and hence complex. Also, not all factors are controllable which makes control of controllables, crucial.
3. The distortion of the external appearance accompanying it diminishes social acceptance and self-esteem.
4. It affects most organs and systems adversely and can cause, inter alia, cardiovascular disease, kidney and liver disease, cancers, diabetes, bone-bone and bone-muscle joint problems.
5. Interestingly, it is measurable simply by following your BMI; it is the most ‘material’ of all chronic ailments that we will soon dive into. You can never be in doubt about your obesity status.
6. It progressively limits its most effective counter – physical exercise i.e. is self-perpetuating.

A rare disease with multiple causes and effects.

‘Prevention is better than cure’ was never more meaningful.

The essential ‘dietary’ nature of obesity: Medical science recognizes ‘genetic’, ‘hypothalamic’ and ‘dietary’ as the three types of obesity based on patho-physiology. Essentially, they can be interpreted as: originating in the genetic make-up of the subject and/or hypothalamic malfunction (Hypothalamus – a part of the brain – controls our hunger and satiety) and/or be the result of flawed diet in terms of quality and quantity.

From a practical and basic stand-point, however, we will deem it as purely ‘dietary’ since it is the digestion, absorption and metabolism/storage of food constituents entering the GI tract that de facto precipitates obesity and dynamically grows it or diminishes it as in slimming. The other factors will be treated as ‘influencers’ of food intake; the hypothalamus malfunction can distort food intake and the genetic make-up can distort metabolism i.e. efficient or flawed use of nutrients.

Exercise or aerobic activity is the counterpoise to diet; we will soon see that it must always be seen in combination with the diet to make sense as an obesity prompt.  This ‘multi-factorial’, but essentially dietary nature of obesity, is a functional but rigorous simplification designed for this blog.

Metabolism and obesity: We know how our diet sends glucose, fatty acids (and glycerol) and amino acids – products of digestion of macronutrients (along with some micronutrients) – into the blood stream across the walls of GI tract. (Ref Posts 2,3: HEALTH, HAPPINESS, LIFE AND FOOD (PART I) : WHAT ARE THEY? and HEALTH, HAPPINESS, LIFE AND FOOD (PART II) : DEFINING ‘FOOD’ AND USING IT SMARTLY as well as Post 14: WATER, FOOD AND LIFE, PART II : THE REMAINING FACETS OF WATER). These molecules carry ‘chemical potential energy’ by virtue of their molecular structure which is nothing but a bundle of stable chemical bonds.

Elaborate biochemical processes within our blood, organs and tissues use these as inputs to generate energy for mechanical and brain-work and heat to maintain body temperature, repair damaged tissue, build new tissue for growth and synthesize enzymes, hormones and neurotransmitters. Note: 

1. Most of our vital organs (heart, lungs, kidneys, liver, pancreas, spleen, bones, brain…) which function without our conscious effort, need calories to function. Obviously this requirement exists even when we are asleep and is called Basal Metabolic Rate – about 2/3 of our total energy requirement because it continues round the clock.
2. A little less than 1/3 is required for our voluntary muscle and brain work (walking, running, swimming, daily chores, thinking and studying….).
3. The remainder small part maintains our body temperature by generating heat.
4. Let’s understand this entire requirement as ‘metabolism’ and ‘build up’ or ‘synthesizing’ as a part of it. It is essentially sustenance of life itself with the help of external inputs: food, water and oxygen/air – stunningly, all three states of matter!

The breakdown processes use reactions with oxygen (oxidation) to unleash the aforesaid ‘potential energy’ which helps us do everything we do. (Ref. Post 15: OXYGEN, FOOD AND LIFE : PART I (HOW OXYGEN MEDIATES IN LIFE AND FOOD PROCESSING). The escaping products – carbon dioxide and water have minimal residual energy making maximum energy available. Interestingly, this is no different in the steam boilers burning coal or any other fuel. Continuous, life-sustaining release of energy for the body as a whole requires such processes to dominate. The buildup and repair of tissue from proteins and re-synthesis of carbohydrates and fats for storage happen on a smaller scale from surpluses and for the ‘rainy day’.

Those potential energy-laden molecules from the diet which are small enough to be absorbable across the GI tract wall are produced by digestion – distinct from metabolism – of our food intake. It produces the residue which is excreted out as feces. The products of metabolism are excreted thru urine (which makes it a potent source of info on metabolic diseases), breath and sweat. Clear distinction: digestion ends in absorption and defecation; metabolism, in energy/heat/build-and-repair and excretion thru urine, sweat and breath.

Metabolism includes  processes that enable storage of surplus products of digestion in our body in proper form and at strategic places – a lot like putting money in the bank for ‘use when required’, obviously a critical function. Nature has chosen the most energy-dense nutrient that can be stored in a large enough quantity so that its corresponding energy supply lasts long enough to tide over a protracted supply crisis. (Ref Post 19: THE PHYSIOLOGICAL FUNCTIONS OF EDIBLE OILS – THEY DO A LOT FOR US WITHIN OUR BODY). That nutrient is fat; re-synthesized from fatty acids and glycerol as well as, believe it or not, glucose! Unfortunately it can become excessive under some well-defined circumstances and thru some complex processes. This is obesity from the metabolic point of view.

The entire gamut of processes – digestion, absorption, metabolism and excretion – supported by organs, blood, water that we drink and oxygen that we breath is what sustains and grows life.  Chemical technologists cringe at the prospect of making reactions happen among solids, liquids and gases together, to produce value-added things; nature does it effortlessly and continuously. That’s a humbling thought and a possible source of inspiration for those cringing creatures!

Glycerol produced by digestion of oil/fat in the small intestine (only about 10% of the intake, rest is fatty acids) is an unobtrusive molecule which the body uses to re-synthesize fats in the body for storage and for conversion to glucose in the liver which is released into the blood for use. It is also produced (as in intestinal digestion) when stored fat in adipose tissue is hydrolysed to produce fatty acids and glycerol, to be used for energy release – the withdrawal from the bank described above. We will simplify our narrative by ignoring this inconsequential player to be able to focus better on the more consequential glucose, fatty acids and amino acids.

Expanding our understanding of obesity: It is more a ‘chronic condition’ of our body creeping up on us gradually thru a series of factors, than a disease. We will focus on these factors later and realize that we can control obesity but to a limited extent. This is why the victims plead helplessness and trying to help them is a multi-billion dollar industry.

We instinctively know that obesity is essentially ‘being overweight’ and is quantified thru the well-known ‘Body Mass Index’ or BMI – the number derived by dividing the weight of the individual in kgs with the square of his height in meters. I weigh 78 kgs and am 1.82 meters tall, so my BMI is under 25. The following is the current classification of obesity on BMI basis:

BMI up to 25…………………………………………………………………normal

BMI from 25 to 29………………………………………………………..overweight

BMI from 30 to 40………………………………………….conventional obese

BMI above 40…………………………………………………morbidly obese

Late Dr. Hathi of ‘Tarak Mehta ka ulta chashma’ was morbidly obese and so are Japanese sumo wrestlers. It is difficult to figure out what happens first: loss of ability or the will to fight.  An analogy with a race downhill is apt.

To encapsulate : 1. Obesity is noticeable ‘accumulation of mass’ within our body over a period of time.

2. This accumulation can come from muscle build up from amino acids and growth of tissues and organs in a young body. This is obviously not obesity, actually the opposite. The storage of glucose as glycogen in the liver and the muscles is very limited and variable, hence does not count. Oil/fat is what’s left!
3. As noted above, the difference between the dietary input of glucose and fatty acids and the consumption for daily energy uses (i.e. the surplus of input over consumption) is stored. This is obesity development; obviously, the withdrawals from storage during a time span (∆t) must be subtracted for ‘net’ obesity development. Note: Surplus glucose also converts to fat in the body.
4. Glucose and fatty acids have the carbon-hydrogen-oxygen (C, H, O) framework in molecular structure. While glucose is the most efficient, instant and ‘popular’ energy source, fatty acids burn slower to release energy, that too, in later stages of requirement i.e. when physical activity is sustained determinedly. This promotes fat accumulation for subjects with low-to-average levels of activity. This also adds fats converted from glucose to the storage if the subject is fond of his biscuits, sweets, ice-cream, bread, chocolates, samosa, even tea…….
5. These input-consumption phenomena are dynamic i.e. they have average ‘time rates’ of the type, dx/dt. In plain words, suppressing input rate and accelerating consumption rate is the most obvious obesity fighting strategy, as we know from common sense.
6. We know from experience and observation that accumulation by musculature development from amino acids derived from proteins is not obesity – the opposite. Proteins are rarely pressed into energy release; their roles have been noted above. In fact, the most muscular and lean body also has adequate fat reserves in the adipose tissue for emergency.
7. Even the leanest body has stored reserves of fat under the skin and in muscles, as nature’s precautionary measure; in that sense, it has ‘minimal’ rather than absent or negative obesity.

Understanding obesity thru a simplified quantitative model: The bio-chemical mechanisms of obesity development have already been adequately simplified above. The details will follow in the next post. In the meanwhile, we have developed a ‘mathematical model’ as a separate helpful simplification to spread its understanding.

The overall ‘material balance’ for a time span, ∆t (week or month),

(Food + water intake), (i) – (all excretions), (ii) – (life-sustaining consumption by metabolism, essentially escaping carbon dioxide and generated water – liquid as well as vapor), (iii) → Accumulation or increase in body weight, ∆m, ( iv).

(The use of arrow in place of equality (=) sign is deliberate.)

If dx/dt is the average rate of net addition of the nutrients to the blood and dy/dt, of metabolic consumption, [dx/dt – dy/dt]∆t = ∆m.

Notes: 1. dx/dt is obviously a function of food intake and dy/dt of growth and activity levels. 2. Ignored here: a. Minor changes in blood volume because of water input-output imbalance, b. the miniscule quantity of oxygen (breathed in) by mass for combustions and c. muscle- and tissue-building addition of weight. 3. There will be both transfer to and from energy storage during ∆t giving rise to a net addition or subtraction for ∆t. The addition to blood stream from food is adjusted for this. 4. For ∆m above to be large (i.e. obesity development to be noticeable), ∆t and dx/dt should be large and dy/dt, small.

When [(i) – (ii)] > (iii), ∆m > 0 i.e. obesity development.

When [(i) – (ii)] < (iii), ∆m < 0 i.e. slimming by withdrawal of stored nutrients for combustion and energy release. 

Let us now understand obesity with a detailed look at how our food intake is controlled, how digestion and absorption fan out combustible nutrients throughout the body, how they perform the energy-producing and building roles and how flaws in these processes lead to obesity.

Next Post:

Obesity and food – accumulation of the unused: Part II

Details of how the food-obesity linkage plays out

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