Metabolism and the Hypothalamus

           The hypothalamus is an extremely vital organ involved in automatic bodily functions.  It regulates the autonomic nervous system (including automatic and/or subconscious).  Neurons in the hypothalamus produce hypothalamic neurotransmitters, which deliver information and instructions to all parts of the human body. (The role of the hypothalamus in hunger).  The hypothalamus is a integral part of “homeostasis regulation, thirst and hunger cues, body temperature, water balance, blood pressure, and links the nervous system to the endocrine system” (Farr, G).

There are three regions of the hypothalamus that are a part of the production of hunger cues.  These include:  the lateral hypothalamus (responsible for hunger recognition), the ventromedial hypothalamus (responsible for recognizing when a person is full), and the paraventricular hypothalamus (Responsible for the control of hunger).  Each of these hypothalamus regions produce hypothalamus neurotransmitters and neurohormones, which control the delivery of instruction that activate a specific body function.  The hypothalamus primarily produces ghrelin and leptin, which signals/relays that the body is hungry or full. 

          

     Ghrelin:  Ghrelin is a fast acting hormone that regulates feeding behavior and the body’s energy balance by increasing hunger feelings.  This can be validated by examining studies that show an increase in plasma ghrelin concentration in fasting adults.  Also, other subjects participating in the study, were injected with ghrelin experienced extreme hunger.  The secretion of ghrelin begins when blood sugar levels drop, a result of not eating for an extended period of time.  “The hypothalamus receives the message through glucostatic receptors”, (Nakate, S).  The low blood sugar triggers/stimulates the secretion of ghrelin, which results in feelings of hunger.  There is speculation that some obesity cases are related to abnormally high levels of ghrelin secretion, which would not only increase hunger, but also “suppress fat utilization in adipose tissue” (Farr).  After eating, the ventromedial hypothalamus will recognize when blood sugar levels begin to rise to normal levels, and leptin is synthesized, causing fullness feelings to be experienced and release of ghrelin decreases.

     Leptin:  Leptin is a fat hormone (produced by adipose cells), responsible for long- term energy regulation.  Leptin mediates fullness feelings, by triggering the activation of anorectic nerve cells, which begin to synthesize appetite-suppressing neuropeptides.  Scientific evidence points to the theory that people who suffer from obesity are leptin-resistant or leptin-deficient.

Active research in the area of neurotransmitters and neurohormones is at the forefront in the subject weight-control.  If there is a way to control the secretion of ghrelin and leptin, some people struggling with weight maintenance may successfully regain bodily health and normal hunger/fullness cues.

References.

Farr, G. (2002). The hypothalamus. The Nervous System-Advanced Version.  Retrieved from http://www.becomehealthynow.com/article/bodynervousadvanced/956/.

Nakate S. (2010). Hypothalamus Function. Buzzle.com. Retrieved from http://www.buzzle.com/articles/hypothalamus-function.html.

The role of the hypothalamus in hunger. (2010). Hellolife:  Matching Your Commitment to a Healthy Lifestyle. Retrieved from http://www.hellolife.net/explore/weight-loss/the-role-of-the-hypothalamus-in-hunger/.

Klok MD, Jakobsdottir S, Drent ML. (2007). The role of leptin and ghrelin in the regulation of food intake and body weight in humans. Pubmed.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/17212793.

Metabolism in the Shadow of Age

There are many studies examining how age affects a person’s metabolic rate.  It’s obvious that many people gain weight as they age but are they using age as a scapegoat?  Could it be that each individual is responsible for his or her metabolism, baring those suffering from a medical condition that affects metabolic rate, like hypothyroidism or hyperthyroidism.

The question does not have an “either/or” answer though.  As we age the mitochondria in our body’s cells slow down, which means that fewer nutrients are being converted to energy powering the body.  With age, risk of sarcopenia, “muscle wasting”, increases substantially.  Barry Stein, from Wake Forest University School of Medicine explains, “Since muscle burns more energy than fat, this means the metabolic load goes down and metabolism reflects that.”  In addition to a body’s mitochondrial cells slowing down, the majority of people, especially in the US, reduce their physical activity as they age, (and for other reasons than a reduced amount of energy).

The good news is that there are preventative techniques linked to physical activity and muscle mass that can be successful in stopping, and even reversing muscle wasting, which in turn increases metabolic rate.  “That European Working Group on Sarcopenia in Older People (EWGSOP) has developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia.  For the diagnosis of sarcopenia, the working group has proposed using the presence of both low muscle mass + low muscle function, strength and performance” (Gassaniga, M).  Some of the suggestions for reducing the effects of sarcopenia are discussed next.

1)                     The best thing that a person can do for their metabolism is exercise.  Because muscle cells burn substantially more calories than fat cells the majority of daily energy expenditure doesn’t occur when people fail to exercise and lose more and more muscle mass each year.  There is also proof that physical exercise increases the number of active mitochondria in the body, which increases metabolic rate.

So, be careful how much you slow down as you enter your 40’s, 50’s, and 60’s; staying active will promote your health and weight-maintenance.

2)                     Avoid skipping meals or eating only 2-3 large meals/day.  After a few years of that diet schedule, your body will begin to conserve more calories from each meal, because going for long periods of time, like 5,6, 7, or even more hours without eating, sends your body into the beginning of “starvation mode”.  As the body enters this mode, the metabolism slows way down so as not to waste the energy from the nutrients of the last meal.  Eating small meals more frequently efficiently forces your metabolism to keep moving at a steady rate throughout the day, frequently having to digest each small meal.  (Also, after not eating for several hours, the body feels more hungry than usual and this can lead to overeating, at the same time as your body’s cells are conserving energy.)

3)                     Drink water and/or green tea.  Studies have provided evidence that drinking 4-5 cups of green tea each day may increase a person’s metabolism slightly.

So don’t just lie down and let age slow you down with weight and weight-related illnesses.  Stay active and fight back!

References

Gazzaniga, Marin. (2010). Slow Burn:  how aging affects metabolism. MSN. Retrieved from http://health.msn.com/fitness/articlepage.aspx?cp-documentid=100119089.

No Author. (2006). Fight your slowing metabolism as you age. Health and Fitness Vitality. Retrieved from http://www.healthandfitnessvitality.com/blogs/2006/11/fight-your-slowing-metabolism-as-you.htm.

Hypothyroidism: who has it?

        Many people complain that their metabolism is slow, however, only people suffering from hypothyroidism actually understands the extent of a truly “slow metabolism”, as they’re forced to deal with challenges and complications in their diet every day.  Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3).  T4 and T3 are tyrosine-based hormones and their primary function in the body is metabolism regulation.  So, when the thyroid gland is producing enormous amounts of T4 and T3, the metabolism rises and extra calories are burned as a result; and when only scarce amounts of T4 and T3 are being produced, the metabolism is greatly reduced and fewer calories are burned by the body.

Today, hypothyroidism is a growing problem; medical experts say that up to 10% of women in the US are affected by hypothyroidism to some degree and total estimates are as high as 10 million Americans!

There are several different diseases and conditions that cause hypothyroidism, the most common being inflammation of the thyroid gland and autoimmune thyroiditis (also known as Hashimoto’s thyroiditis).  The thyroid gland lies just below the larynx in the front of the neck; continued inflammation of the thyroid gland or surrounding neck region can result in serious damage to the gland’s secretory cells, which are chiefly in charge of thyroid hormone excretion.  Autoimmune thyroiditis is a chronic condition in which the body’s immune system attacks the thyroid gland.  Other causes of hypothyroidism include:

·      Medical treatments including radiation or surgery to the neck in cancer treatment.

·      Congenital Birth Defects

·      Radioactive iodine, which is often used to slow down the metabolism in the case of hyperthyroidism.

·      Lack of thyroid stimulating hormone (TSH), which is produced by the pituitary gland.  (Often individuals with this problem have completely normal/healthy thyroid glands.)

·      Certain pharmaceutical drugs

There are certain symptoms that can help a person recognize that they might be having thyroid problems.  Some of these include:  weakness/fatigue; coarse, dry and cracked skin, hair and nails; sensitivity to cold; irritability and depression; memory loss; lowered sex drive; increased susceptibility to other diseases like diabetes; and of coarse…Weight Gain and difficulty losing weight.

            There have been, and continue to be, new and promising diets for hypothyroidism patients.  Among the most successful is the “Zone Diet”, which emphasizes balancing a diet using the ratio 40:30:30 for carbohydrates, proteins and fats, respectively, as well as limiting intake of simple carbohydrates like bread and pasta.  Limiting carbohydrate intake is a key point.  When carbohydrates are consumed, blood sugar rises and, the pancreas secretes insulin to bring it back into a normal range.  If a person consumes a large excess of carbohydrates, the pancreas releases more insulin than normal to bring the body’s blood sugar back down.  Often the pancreas releases so much insulin that blood sugar level drop below normal.  The Zone diet teaches people that while the pancreas is busy secreting large amount of insulin, the body is unable use any stored fat reserves.  When this happens often, weight is gained and often diabetes is right around the corner.  Hmmm, could this be the reason that low fat diets don’t work?...

            So, if you are suffering from hypothyroidism, remember that every case is individualized and not every diet or medication that works for one person with have the same positive affects on another person.  Curb you carbs intake and try to relieve all types of stress in your life, as this too, can increase insulin production and send you back into a vicious cycle.

References

Nippoldt, Todd, M.D. (2010). Is there any truth to the hypothyroidism diet? Mayoclinic. Retrieved from http://www.mayoclinic.com/health/hypothyroidism-diet/AN01478.

Norman, James, M.D. (2010). Hypothyroidism:  too little thyroid hormone. Endocrineweb. Retrieved from http://www.endocrineweb.com/conditions/thyroid/hypothyroidism-too-little-thyroid-hormone.

Shomon, Mary. (2003). The zone diet for thyroid patients and losing weight with hypothyroidism. Retrieved from http://thyroid.about.com/cs/dietweightloss/a/zonediet.htm.

Water: A Metabolism Booster?

There have been claims that drinking water will increase your metabolism, and lead to further weight loss in a diet.  However, doesn’t it sound a little too good to be true?  Water, one of the most fundamental compounds on the earth…is the answer to the ever-present, growing weight loss problem? 

            The human body requires water to carryout tons of physiological functions.  In fact, water accounts for 2/3 of a person’s body weight.  Specifically, water makes up 90% of a body’s blood plasma, which accounts for most fluctuations in blood volume.  Blood is the main transporter of oxygen, carbon dioxide, hormones and bodily waste.  Most of the time when the blood volume decreases, it means that the plasma volume has been reduced, usually from dehydration.  This results in a smaller stroke volume, (the amount of blood being pumped by the heart in one pulse), and can lead to a temporarily lowered blood pressure.  If there is only a minimal amount of blood being pumped throughout the body, the cells, tissue and organs will only receive the minimum amount of oxygen.  This restricts the nutrients that the cells are able to metabolize to function properly.  When the body is properly hydrated, the blood volume remains stable and the body tissues receive enough oxygen to metabolize maximum nutrients…which burns more calories.  But how many calories are we talking about here?

The answer to this question varies somewhat.  An article published in 2003 in the Journal of Clinical Endocrinology and Metabolism discussed a study in which healthy participants (men and women), drank 500 ml water/day.  Immediately after drinking the water, the participant’s metabolic rates were monitored to determine whether water would affect it.  The study found incredible results.  All of the participant’s metabolic rates increased by thirty percent within the first half hour of drinking the water and remained high for one hour after water consumption.  These results supported that when a person drinks 8 glasses of water each day, they have the potential of burning 70 additional calories had you decided not to drink any water. 

So why does this happen?  The answer is actually not that complicated.  When we bring something cold into or against the body, heat is transferred to the cold object until the body and cold object have the same temperature.  When you drink water, especially ice water, the body is having to work harder and requires more energy to maintain body temperature.

Now this does not mean go chug cold water; that can be dangerous and increase blood volume to unsafe levels.  However, if you follow the simple “8 glasses of water” rule, you will burn a few more calories each day, and after several years, it adds up!

References

Barth, Christy. Give you metabolism a boost. (10/9/2010). Retrieved from http://livebreathenutrition.blogspot.com.

Jordan, Jennifer. Drink, drink, drink…how water increases metabolism. (11/4/2010).  Retrieved from http://ezinearticles.com/?Drink,-Drink,-Drink---How-Water-Increases-Metabolism&id=1001158.

Keefer, Amber.  Does drinking water increase metabolism? (11/4/2010). Retrieved from http://www.livestrong.com/article/30240-drinking-water-increase-metabolism/.