There are many factors that can decrease body temperature such as CR, fasting, estrogen, stress, pollution, over exercise and more. CR has been suggested as a mechanism for maintaining longevity but studies lack any conclusive evidence (Carrillo & Flouris, 2011) and a theory that a cold body, decreases metabolism, oxidation and damage therefore preserving tissues. Another emergent theory and results show in rodent studies, that mammals with a high energy intake, high metabolism and organised biology can increase life span (John R. Speakman et al., 2004) (J. R. Speakman, 2005). Think about this for a minute:
Calorific restriction makes the body cold, decreases metabolic rate (via inhibition of thyroid hormone) and disorganisation of tissues. Entropy State
Adequate energy, maintains body temperature and organises tissues to function at their best. Negative entropy state.
From an evolutionary perspective fasting due to lack of food was a necessity. Fasting these days could be a useful tool, if you were prone to constant overeating but if your system lacks the flexibility to do so problems can occur. That’s not to say that calorie restriction for weight loss isn’t helpful but sustained CR in a system that doesn’t respond well might be counterproductive. Pollution has increased at a phenomenal rate clearly affecting physiology and hormones (Gore et al., 2015). Does it make sense that a so called detox diet, low in calories, protein, carbohydrates can enhance the function of detoxification, when liver function is energy and thyroid dependant? Skipping breakfast alone in some is associated with increased cortisol, glucagon and metabolic inflexibility (Jakubowicz, Wainstein, Ahren, et al., 2015) (Jakubowicz, Wainstein, Ahrén, et al., 2015). These factors can also decrease the mitochondrial uncoupling proteins which are responsible for increased body temperature.
Ageing is also associated with decreased metabolic rate, colder bodies and accepted increases in thyroid hormone stimulating values (TSH) (Laurberg, Andersen, Pedersen, & Carlé, 2005) . If symptoms of failing biology are present with isolated thyroid symptoms such as increased cholesterol, , high blood pressure and sugar, cardiovascular issues and even cancer the acceptance of TSH and other thyroid hormone analysis to accurately predict hypothyroidism should be considered. Body temperature and metabolic rate was reliably used in the last century to diagnose hypothyroidism with qualitative analysis of symptoms and symptoms resolved with thyroid hormone treatment (Barnes, 1942) (McGavack, Lange, & Schwimmer, 1945) (Peat, 1999). Whilst thyroid is useful for restoring function, food and other factors can be used to restore and maintain function (previous blog on maintaining the aerobic system)
Certain nuances exist in temperature regulation that are dependant on acute or chronic exposure to stressors and a slowing down of the system through a functionally, subclinical or overt hypothyroid state. In short term fasting, TSH is initially raised then decreases, negating thyroid blood tests. In the same manner the time frame of any stressor can dictate whether short or long term compensations of the sympathetic adrenergic system is supporting the system. In well established feedback mechanism it’s known that as TSH increases so does cortisol and as body temperature approaches hypothermic levels (around 35C) cortisol, adrenaline and noradrenaline can increase body temperature as a protective response.
In a world where excess environmental and social stressors are ever increasing - it might make sense to maintain an efficient, organised warm body rather than reducing its function and heat.
Barnes, B. (1942). Basal temperature versus basal metabolism. Journal of the American Medical Association, 119(14), 1072–1074. http://doi.org/10.1001/jama.1942.02830310006003
Bicego, K. C., Barros, R. C. H., & Branco, L. G. S. (2007). Physiology of temperature regulation: Comparative aspects. Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology. http://doi.org/10.1016/j.cbpa.2006.06.032
Carrillo, A. E., & Flouris, A. D. (2011). Caloric restriction and longevity: Effects of reduced body temperature. Ageing Research Reviews. http://doi.org/10.1016/j.arr.2010.10.001
Gore, A. C., Chappell, V. A., Fenton, S. E., Flaws, J. A., Nadal, A., Prins, G. S., … Zoeller, R. T. (2015). Executive Summary to EDC-2: The Endocrine Society’s second Scientific Statement on endocrine-disrupting chemicals. Endocrine Reviews. http://doi.org/10.1210/er.2015-1093
Jakubowicz, D., Wainstein, J., Ahrén, B., Bar-Dayan, Y., Landau, Z., Rabinovitz, H. R., & Froy, O. (2015). High-energy breakfast with low-energy dinner decreases overall daily hyperglycaemia in type 2 diabetic patients: a randomised clinical trial. Diabetologia, 58(5), 912–919. http://doi.org/10.1007/s00125-015-3524-9
Jakubowicz, D., Wainstein, J., Ahren, B., Landau, Z., Bar-Dayan, Y., & Froy, O. (2015). Fasting until noon triggers increased postprandial hyperglycemia and impaired insulin response after lunch and dinner in individuals with type 2 Diabetes: A randomized clinical trial. Diabetes Care, 38(10), 1820–1826. http://doi.org/10.2337/dc15-0761
Laurberg, P., Andersen, S., Pedersen, I. B., & Carlé, A. (2005). Hypothyroidism in the elderly: Pathophysiology, diagnosis and treatment. Drugs and Aging. http://doi.org/10.2165/00002512-200522010-00002
McGavack, T. H., Lange, K., & Schwimmer, D. (1945). Management of the myxedematous patient with symptoms of cardiovascular disease. American Heart Journal. http://doi.org/10.1016/0002-8703(45)90476-5
Peat, R. (1999). Thyroid Therapies, Confusion and Fraud. Retrieved from www.raypeat.com/articles/articles/thyroid.shtml
Speakman, J. R. (2005). Body size, energy metabolism and lifespan. Journal of Experimental Biology. http://doi.org/10.1242/jeb.01556
Speakman, J. R., Talbot, D. A., Selman, C., Snart, S., McLaren, J. S., Redman, P., … Brand, M. D. (2004). Uncoupled and surviving: Individual mice with high metabolism have greater mitochondrial uncoupling and live longer. Aging Cell. http://doi.org/10.1111/j.1474-9728.2004.00097.x