Achieving Energy Balance for Weight Loss and Improved Health | Mukaila Kareem, DPT | RxEconsult
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Achieving Weight Loss and Improved Health with Energy Balance from Physical Activity and Diet Category: Diet & Weight Loss by - January 6, 2015 | Views: 27196 | Likes: 0 | Comment: 0  

Energy balance and weight loss

Modern Lifestyle and Weight Gain

Most adults complain of weight issues and have some extra fat they would wish away. In contrast to our ancestors, we are living in a conquered environment with plentiful foods and sedentary occupations. The population of farmers is extremely small and they are mostly invisible in our everyday lives but produce far more than we can consume. At the highest level of productivity, millions of dollars can be made in front of the computer by the click of a mouse.

Unfortunately, these twin factors of abundant foods and sedentary lifestyle are not opposed by biology. In other words, our body does not work against overfeeding or discourage physical inactivity but strongly defends against weight loss. This explains why there is continuing rise of obesity and overweight people across gender and age strata.

Total Energy Balance

According to the first law of thermodynamics, energy can neither be created nor destroyed. This physical law is also applicable to human physiology. Energy intake can either be used up or stored away as body fat. It therefore follows that sustained excess food consumption results in overweight and obese states. For better understanding, the total body energy expenditure (TEE) in a 24-hour period is divided into basal metabolic rate (BMR), thermic effect of food (TEF) and activity thermogenesis (AT). BMR is the energy needed to maintain life at rest and is about 60-70% of TEE while TEF is about 10% of TEE and is the energy required for food ingestion, digestion, absorption and storage. The third and the most variable component of TEE is AT and accounts for both leisure-time exercise and unstructured daily physical activity otherwise referred to as non-exercise activity thermogenesis (NEAT).

Regardless of gender, age or genetic constitution, anyone who stops eating would lose weight. Also, if life sustenance through food consumption is occasional or as repulsive and disgusting as taking bitter medicines, this article would not be necessary. The fact is food consumption is pleasurable and regularly needed. Humans are attracted to pleasurable experiences and restricting food is therefore not feasible long term. On the other hand, dispensing energy through structured or unstructured activity is tedious and demands physical exertions and of course is not pleasurable. When energy intake (pleasurable food consumption) is more than energy expenditure (tedious physical exertions) over a period of time then there is increase in weight.

Structured and Unstructured Physical Activity

Since the dawn of industrialization to date, there has been increase in energy intake and progressive decrease in physical activity. For instance, the increase average daily energy intake from 1971 to 2000 was a whopping 168 and 335 kilocalories per day, for men and women respectively. On the other hand, a 2012 review of previous works reported that the average daily steps of adult Americans are 5,000 per day which is 13,000 and 9,000 steps less than the number of steps for Amish men and women respectively. A 2008 study also found that the US population spends 7.7 hours or 55% of their day in sedentary behavior. Furthermore, the estimated daily occupation-related energy expenditure has fallen by more than 100 calories for both women and men, causing significant increase in mean US weight during the period 1960 to 2008.

Weight Loss versus Weight Maintenance                                    

The talk of weight loss is often centered on diet or some highly intense exercise fad that is not sustainable for most individuals. Energy balance is realistically achieved by coupling energy intake with moderate to vigorous physical activity. Diet alone will cause weight loss but the body will compensate by reducing production of the appetite suppressing hormone (leptin) and increasing levels of appetite stimulating hormone (ghrelin). This will ultimately stimulate hunger and eventual “fall off the wagon” because food is plentiful.

 Weight maintenance precedes weight loss and weight loss occurs over a period of time. It seems that everyone wants to lose weight very quickly and almost always give up too soon if volitional structured exercise does not produce dramatic weight loss. Since the body strongly vends off negative energy balance, significant weight loss demands significant permanent behavior change. On the other hand, with small behavioral changes, it is easier to keep off weight that has not been gained. According to a 2003 study, walking 15 minutes a day or eating few less bites every meal could expend or decrease 100 kilocalories per day and can prevent weight gain in 90% of the US population. For sedentary office workers, another work done in 2011 reported that standing and walking at normal pace for 2 and 5 minutes once every hour during 8-hour work day could theoretically expend 296 and 660 additional kilocalories per week respectively compared to sitting. This level of energy expenditure, according to this study, is significant enough to cause weight maintenance or even weight loss.                                                             

Weight Maintenance and Health                                                                             

Fortunately, even without physical evidence of weight loss, regular physical activity can control, delay or reduce the risk of diabetes, hypertension, heart attacks and decrease risk of certain kind of cancers. The 2011 study further stated that 150 minutes per week of moderate intensity activity or 75 minutes per week of vigorous activity compensates for reduction in occupation-related energy expenditure over the last 50 years by more than 100 calories per day.

Incorporating short bouts of physical activity throughout the day could promote moderate food consumption and reinforce compliance with federal guidelines on physical activity. Starting with small behavioral changes may lead to sustainable lifestyle of regular physical activity that may lead to weight maintenance and weight loss over time. This approach doesn’t usually disappoint and does not require yearly resolutions.

References

Centers for Disease Control and Prevention (2011). Physical activity and health. 

Church, T. S., Thomas, D. M., Tudor-Locke, C., Katzmarzyk, P.T., Earnest, C. P., Rodart, R. Q., Martin, C. K., Blair, S. N., & Bouchard, C. (2011). Trends over 5 decades in U.S. occupation-related physical activity and their association with obesity. PLoS One, 6(5). 

Hill, J. O. (2013). Understanding and addressing the epidemic of obesity: An energy balance perspective. Endocrine Reviews, 27(7). Retrieved from press.endocrine.org

Hill, J. O., Wyatt, H. R., & Peters, J. C. (2012). Energy balance and obesity. Circulation,126. 

Hill, J. O., Wyatt, H. R., Reed, G. W., & Peters, J.C. (2003). Obesity and the environment: Where do we go from here? 

Kinucan, P., & Kravitz, L. (2006). Controversies in metabolism. 

Levine, J. A., Weg, M. W. V., Hill, J. O., & Klesges, R. C. (2006). Non-exercise activity thermogenesis. Arteriosclerosis, Thrombosis, and Vascular Biology, 26

 Matthews, C.E., Chen, K. Y., Freedson, P. S., Buchowski, M. S., Beech, B. M., Pate, R. R., & Troiano, R. P. (2008). Amount of time spent on sedentary behavaviors in the United States, 2003-2004. American Journal of Epidemiology, 167(7). 

 Swartz, A. M., Squires, L., & Strath , S. J. (2011). Energy expenditure of interruptions to sedentary behavior. International Journal of Behavioral Nutrition and Physical Activity, 8.                                  

 



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