Week 8: Lecture 38: Energy Balance, Food Environments, and Weight Regulation

Hello and welcome dear learners to the NPEL course on nutritional epidemology a way towards a healthy life. For the module 4 diet, nutrients, dietary patterns and discuss epidemology. For the chapter 38 we'll be talking about energy balance, food environments and weight regulation. So here we'll be discussing about principles of energy balance, determinance of energy intake and expenditure, the biological and behavioral influence of food choices, food environments and obesogenic settings. The physical activity and sedentary behavior challenges in obesity prevention followed by key takeaways will be taken. Now we'll understand the principles of energy balance. The fundamental biohysical framework governing the weight regulation rest on the first law of thermodynamics. Energy can neither be created nor destroyed only transformed. In human physiology, this is expressed through a dynamic energy balance equation. What is the equation? It is energy store is equal to energy intake minus by energy expenditure. The fallacy of the static model. Historically, public health relied on the static model of energy balance that is traditional 3,500 calorie rule. which incorrectly claim that cutting 500 calories a day could lead to a predictable linear weight loss of one pound per week indefinitely. The modern metabolic research has completely discredited this static view. The body operates as a dynamic adaptive system. When calorie intake drops, the body initiates metabolic adaption. Adaptive thermogenasis happens downregulating energy expenditure to defend its fat stores. This means that weight loss naturally flat weights making long-term weight regulation for more complex than simple arithmetic. The carbohydrate insulin model versus the energy balance model. Epidemologist and endocrinologist are currently debating on the two core models of obesity. What is the first model? The energy balance model. It argues that obesity is driven by over supply of energy dense food which overstimulates the central appetite pathway and lead to an excess of energy intake over expenditure. The carbohydrate insulin model is a second model which postulates that consuming high glycemic carbohydrate drives up insulin secretion processing fuels away from circulating blood and trapping them in the fat tissue starving vital organs and triggering a secondary increase in hunger and a drop in metabolic rate. So these are the two models. The determinance of energy intake and expenditure. The total energy that we are taking daily and its expenditure is divided into three distinct metabolic compartments. One is the basil divided by resting metabolic rate that is BMR which accounts for 60 to 70% of your total daily energy expenditure. This is the baseline energy required to maintain involuntary cellular hemoasis, cardiovascular function and respiration at complete rest primarily driven by fat-free mass. The thermic effect of food which accounts for roughly 10% of the total daily energy expenditure. It represents the metabolic cost of digesting, absorbing and processing nutrients. Protein requires the highest energy invested to digest that is 20 to 30% of its energy value followed by carbohydrate which takes 5 to 10% and dietary fats that is 0 to 3%. So the total physical activity which accounts for 15 to 30% of the total daily expenditure. This is the most palatable compartment and it is splitted into energy activity thermogenesis and nonex exercise activity thermogenis. The total daily expenditure a multiffactorial analysis where you can understand the basal resting metabolic rate that is BMR is 60 to 70% the total physical activity TPA is 15 to 30% and the thermic effect of food that is of 10%. And it is being represented that how the thermic effect is coming from energy used for digestion, absorption and assimilation of food where you find the physical activity, the non-ex exercise activity and energy for life sustaining functions like respiration, cell production and maintenance. Now we will try to see what is the mathematical determinant of TDE that is the international standard to transition from theoretical compartments to clinical and field application. Epidemologists have used validated productive equations to estimate an individual's caloric requirement and they are based on four key inputs. The first key input is weight. Second is height. Third is age and fourth is biological sex. Now in step one calculate the basal metabolic rate that is BMR. The mifflin stair jaw equation is globally recognized as the modern clinical gold standard for predicting resting energy needs in both healthy weight and obese population. where in case the BMR for male is equal to 10 W + 6.2H - 5 A + 5 where the BMR in female is 10 W + 6.25H - 5 A - 161. So you can understand over here how this international field studies through our estimating the needs that individual require with the high ediposity. Now in the step two, in the step two the parameter and variable analysis which is like an applying this equation correctly in a clinical or field research setting. The input coefficients and biological adjustment must be defined precisely where mate must be entered strictly in kilograms, height must be entered strictly in centimeters and age must be entered in years. The reason is that it should not underestimate or overestimate if the inputs are not given proper way. Difering the mil coefficient where the weight multiplier is like 10 W where represents a baseline metabolic cost of maintaining a total mass at rest. Every kilogram adds roughly 10 kilo calories per day. and a height multiplier that scales the calculation for body surface area. Taller individuals have a larger surface area and burn slightly more energy to maintain the core temperature. Age multiplier for every single chronological year and in individual age they estimate baseline resting metabolic rate drops by 5 calories per day. And same with age sex adjustment serves as the biological paraproxy for body composition. Biological male generally possess a higher percentage of metabolically active lean skeletal muscles while biologically females inherently carry more essential adipos tissue. To adjust for this, the male equation adds a small constant of + 5 while the female equation subtract a significant constant of minus 161. Desper uh revised Harrison's Bendix coefficient which comes with baseline intercepts and accelerated age penalties which the formula are being seen over here where the epidemological limitations come because the Harris Benedict formula was developed using a linear cohort from the early 20th century. It heavily weighs baseline constant and frequently overestimates the calorie needs of modern population living with high amount of body fat. Now we'll see that applying the physical activity level that is pal factor. So you can say BMR only tracks come state survival. So to find the actual total daily calorie consumption, BMR is multiplied by standardized physical activity and the coefficient is designated by WH FO experts energy concentration framework that can be seen. So the TDE is equal to BMR multiplied by PL. Understanding the sedentary, high uh light activity and moderate activity, very activity and extra activity which is giving you a multiplier to give you about the lifestyle translation. What is now the biological and behavioral influence on the food choices? As you understand the hemostatic axis that is leptin, grein and neuroendroine loop which gives us more that the brain tracks short-term and long-terms energy availability via hormones that signals the accurate nucleus of the hypothalamus. So this hormones which is called as leptin is the static hormone which is secreted by the edipos fat tissue where versus the grillin is secreted primarily by the stomach lining and it is during the time of the spike of fasting immediately before the meals to drive the appetite and dropping quickly once the food is consumed and the gut peptides actually are secreted by intestine in response to the nutrient arrival. What do the gut peptides do? They act as a short-term safety value that signals fullness and delay the gastric emptying keeping the nutrient intake into check. So you can understand like how the heatic access takes place which is little rewarding pathways. Here is the demonstration which is given in form of a figure towards understanding the brain track energy availability wherever says deping the send jaws coefficient and leptting long-term godge of body fat and safety also it is giving you more presentation about the sex adjustment biological proxy for body composition from male to female revised strengths of baseline and intercepts shub hunger the hormone where you can see the stomach lining and all and a gut peptides the short-term fullness and intake fullness. Now the hedonic axis and ultrarocess interfaces the modern food choices are increasingly driven by hyonic uh pleasure seeking pathways centered on brains dopamine reward system. You understand the whole play of dopamine is more towards understanding the needs. The ultrarocessed foods what are industrially energized to combine the specific ratios of refined carbohydrates, sodiums and fats. So all this energized by the engineered this combination creates a bliss point that rarely occurs in nature overpowering heostatic statity pathways and causing individuals to continue eating for pleasure even when their biological energy needs are fully met. So it is like creating a bliss point which is giving you that you should eat more and more. Now the food environments and obesogenic setting. So what is this obesoggenic setting that a rapid rise in global obesity cannot be explained by sudden changes in human genetic. Instead it is driven by genetic vulnerabilities exposed to an obesogenic environment defined as a collective physical economical and cultural surroundings that promote weight gain. So you can understand the Sween burns Angelo's framework. So what is SW Swinburn's Angelos's framework? The analysis grid for environment which is linked to basity categorizes the environmental influences across two dimension. One is where you can see the micro environments and the other you can see the macro environments which is coming more from physical, economical, policy and socioultural. where you can understand in the physical you may find that fast food density in a neighborhood, lack of grocery stores with a walking distance and macro environments which is like national transit networks that prioritize cars over pedestrian infrastructure. In economic micro environment local setting the local price gap between the whole food and ultrarocessed food is tremendous. Where was in the macro environments the massive agriculture subsidies for corn, soya, palm oil then keep junks and food cheap. Policy wise the school board rules regulating of competitive vending machine sales in the macro environment. Federal regulations on front of pack nutrition labels and marketing to minors. social cultural where the family habits around screen time, dining and shared meals where versus in the macro environments which is a system uh systematic driven which is a broad cultural shift towards home food delivery apps and convenience dining. So you can understand over here how analyzing the food environment from the local setting versus a systemic drivers affects. Now here we can understand the food deserts versus food swams. Epidemological research highlights that two structural spatial barriers to healthy eating. The food deserts geographic areas where resident lack access to affordable nutritious and fresh food options typically due to a lack of grocery stores and supermarkets. food swams, areas with an overwhelming density of high calorie fast food outlets and convenience store retailing ultrarocessed snacks. Epidemological data indicates that food swams are often stronger predictors of high population level BMI than the food desert alone as unhealthy options actively crowd out nutritious alternatives. Now physical activity and sedentary behavior. The [snorts] physical activity side of the energy balance equation has undergone a massive structural shift due to modern technology and urbanization. How it is affecting the constraint total energy expenditure model where historically the public health assumed that physical activity added linearly to ex energy expenditure. However, the recent evolutionary biology and metabolic data support the constrained energy expenditure model. This model shows that beyond a certain baseline, the human body adapts a higher level of physical activity by downregulating the energy spent on the other internal metabolic process like immune function and tissue repair. This preserves a relatively stable daily energy window. Consequently, while physical activity is essential for cardiovascular fitness, metabolic flexibility, and maintaining overweight loss, increasing exercise alone is rarely an effective strategy for weight loss without dietary changes. Now, you can see the linear energy model where versus a constrained energy model. In the linear energy model, it is shown that there is an activity level where the total expenditure in terms of exercise is replaced and the quantum shift in the metabolic science. This is driven by advanced adaptive optimization which dynamically reallocates energy as illustrated in the updated diagrams. See specifically the enhanced mechanism in the constraint model and that the reallocation network below where you can find the quantum where active movement immune system and basal metabolic adaptation where the total expenditure is more towards a quantum energy reallocation and which is more pointing from a human cell and a mitochondria where you may find that the reproductive reallocation immune and the digestive reallocation also enhanced basal functions where you can see that it is very proven and very active activity level. So the adaptability is more towards this. The sedentary behavior as an independent health risk where a sedentary behavior can cause definitely a walking activities that expend lesser than 1.5 m of energy while sitting. Is it like re reclining or lying down? It is not merely the absence of exercise I mean to say but epidemological cohorts demonstrates that prolonged sitting in an independent risk factor for a type two type 2 diabetes and all cause of mortality. Even for an individual who meets standard weekly exercise guideline, sitting still for a long period shut downs the skeletal muscle lipoprotein lipase that is LPL activity which sharply reduces the body's ability to clear triglycerides and glucose from the bloodstream. Now we will see the challenges in obesity prevention where the key challenges are more highlighted towards the prevention treatment asymmetry where preventing population level obesity is exceptionally difficult due to deeply entrenched biological political and systemic barriers. So these are the three very important uh barriers I meant to say where the biological counterregulation where you can say the weight loss uh triggers body treats loss and extential threat where the physiology is like downregulates and resting metabolism. So obesity prevention is exceptionally difficult due to deep you can say a systemic barriers which is coming that metabolic set points of theory fights to push body weight back to the previous one. Again the prevention treatment asymmetry where public health systems where structural prevention policy and food taxes returns over the decades where you may find that it is more that the downstream medical treatment of beriatric surgery and GLPI triceptors antagonist and you may say immediate visible results which are being seen on the one side which are more positively being taken wherever is the return over decades of reducing the food access no and structural preventing policies are more a public health system. So you may see that immediate visible results and capturing more medical funding where a short-term policy cycles are not to be seen but cannot solve the underlying societal drivers which are to be needed. Then you may see the corporate lobbing and cognitive framing. You may have multinational foods and beverages called muggrates where you may come across that they take a key corporate strategy that lobbying against the public health policies which are being seen over here. The narrative is that it frames obesity entirely around an individual responsibility and physical inactivity just exercise more. So it is more like they are putting more burden on the individual. The shifts of public health focus is away and they spend billions on lobbing this the hyperprocessed food environments which is more the function that a corporate lobbing is doing on. Now at the end of this chapter where the key takeaways are taking that dynamic metabolism energy balance is an adaptive dynamic biological system and not a simple math equation. The body actively adapts its metabolism to defend its fat store. So you can understand that whole that the body is taking more stake on the dynamic metabolism in itself actually to replenish from whole of the factor whereas the environment or willpower actually which is taking more from the structural settings like food spams corporate marketing driven population level weight gain making health outcomes heavily depend on a person's zip code where it is more overly towards understanding like how an individual is being put and blamed for having and control on his own body and strategizing to understand that the obesity is more a responsibility of an individual person. The exercise paradox the regular physical movement is critical for overall metabolic health but sedentary lifestyles create independent risk that exercise alone cannot fully fix. So what you need to do understand over here that you have to even see your diet along with not taking sedentary lifestyle but pushing yourself towards exercise the upstream solution which are coming at last because human biology naturally resists the weight loss where the body will try to overcome and try to maintain the weight where public health must prioritize the upstream environmental and policy interventions which are overall the individual management. management alone. So individual alone cannot be prioritized rather than more upstreaming towards taking environmental and policy interventions are in the hands of the publican. So with this we come and end to this chapter. We can take over the references over here to understand more in deep of this. Thank you. Thank you very much. [music] >> [music]