What is Metabolism and How Does It Change with Age?
By Gary M. Pepper, M.D. and Sam Jeans, MSc
Our bodies undergo many transitions as we age, some good and some not so good!
In the latter category of “not so good”, many people tend to struggle more with their weight as they get older. Obesity rates are higher in older populations, and in the United States, more than 30% of both men and women over 60 are obese.
Obesity in older age brings about much of the same risks as it does at any age, including an increased risk of heart disease, diabetes, high blood pressure, stroke, and mobility problems, and the risks climb ever higher with each year that goes by!
Unraveling what happens to our metabolism as we age helps provide strategies for staying healthy and reducing the risks of putting on excess weight. The popular consensus is that, as we age, our bodies ‘slow down’, which makes it tougher to keep weight off, but does that really tell the whole story?
Metabolism Defined
At its most fundamental, metabolism encompasses every chemical process required to sustain life. It’s easy to confuse the entire concept of metabolism with just the basal metabolic rate (BMR) alone, but this is just one component of metabolism.
Many people use the terms interchangeably, whereas, in fact, there are three main components to metabolism:
1: The Basal Metabolic Rate (BMR)
The body is in constant motion, so even when we’re totally sedentary, sleeping, or otherwise at rest, we require energy and nutrients to function correctly.
So long as the heart pumps, the lungs breathe and the body and its organs go about their business growing and repairing cells, we are utilizing energy in one form or another, and this is our basal metabolic rate (BMR).
The BMR varies depending on the following factors:
Body Size and Muscle: Larger bodies have greater energy demands and higher BMRs.
Lean Muscle Tissue: Whilst it’s true that larger bodies have greater energy demands, BMR also increases relative to the proportion of the body that is made up of lean muscle. Muscle burns more energy than most other tissues.
Body Fat Percentage: Fat burns energy at a much lesser rate than most cells. A high body fat percentage relative to lean muscle tissue results in a lower BMR, even if the body itself is physically larger.
Age: Age does affect the BMR for a few different reasons, which we will discuss shortly.
Growth: Younger children have generally higher BMRs due to body growth, and they also need more energy to maintain their body temperatures.
Gender: Men likely have higher BMRs than women on average as they’re larger and have higher percentages of lean muscle tissue.
Genetics: Genetics do play a role in BMR, but there is debate surrounding quite how drastic the influence of genetics is compared to other factors.
Hormones: Hormone levels, particularly those governed by the thyroid gland, also influence BMR. Hypothyroidism (sluggish thyroid function) is associated with a lower BMR whereas hyperthyroidism (excessive thyroid function) is associated with elevated BMR. Metabolism-related hormones are also influenced by diet, for example, iodine deficiency may result in an underactive thyroid that lowers BMR.
Activity Level: Whilst physical activity burns energy directly as a result of exercise, it also raises BMR by stimulating the growth and repair of new cells, such as muscle cells.
Infection: Infections stimulate an immune response that requires energy, thus boosting BMR.
Environment/Temperature: Colder environments may increase BMR slightly as our bodies work harder to maintain a stable core temperature. Conversely, hotter environments may increase BMR as our bodies work harder to cool down.
2: Thermic Effect of Food (TEF)
The consumption of food itself requires energy and some foods are much easier to digest than others.
It takes considerable effort for our bodies to move food through the digestive system, and our body also needs to absorb and transport nutrients from that food, which further requires energy.
A concept that tends to pop up in various diet plans is ‘calorie negative food’ – that is food that burns more calories to digest than they provide as food. Sadly, there is no evidence that we can ‘eat ourselves thin’ by consuming calorie-negative food!
TEF varies considerably depending on the food consumed and its macronutrients content:
Fat has a thermic effect of some 0 to 5%, which means that for every 100 calories of fat consumed, the body burns just 0 to 5 calories
Carbohydrates have a thermic effect of around 5 to 10%, so for every 100 calories of carbs consumed, the body burns just 5 to 10 calories.
Protein has a much higher thermic effect of around 20 to 30%, so for every 100 calories of protein consumed, the body burns 30 calories (Source: Healthline).
Thirdly, our body requires energy to sustain movement and exercise. This is highly variable and obviously depends on physical activity levels – the more we move, the more energy we require to breathe, fuel our muscles, and repair cells.
Common estimates suggest that physical exercise uses between 15% and 30% of average daily energy expenditure. Engaging in intense or protracted physical exercise ( such as running a marathon) will increase that figure.
The total accumulative energy required for these 3 metabolic components – BMR, TEF, and TEE, makes up our total daily energy expenditure.
In Part 2 of this article, we will cover how aging affects our metabolism and what we can do about it. Check back at metabolism.com for the publication date.
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Much as has been said recently about the health benefits of coconut milk and coconut oil. Coconut milk is a white liquid mixture of water and the white “flesh†of the coconut and is considered a more diluted form of coconut oil a thick clear liquid. Coconut extracts have been used in commercial food products, non-dairy creamers and cooking for many years but lately there has been a burst of publicity for coconut oil and milk as a new form of health-food with beneficial properties including increasing energy, preventing cancer and speeding weight loss. I have seen it being added to ice cream and even bottled water. I want to sound a note of warning here.
Most physicians and nutritionists will advise against having too much fat in the diet for a number of reasons. First, and most obvious, fats have lots of calories. In addition dietary fat can increase the bad cholesterol (LDL) content of the blood leading to increased risk of heart attack and stroke. Among the different kinds of fat that raise LDL the worst are the saturated fats. One tablespoon of coconut oil contains about 120 calories with about 90% of the coconut oil being saturated fat. In fact the saturated fat, palmitic acid, takes its name from the plant that produces coconuts, the palm tree. Compare this to the fat in dark chocolate which is 30% oleic acid, the healthy monounsaturated fat found in olive oil.
Oils which are far more beneficial for preparing foods are unsaturated fats including the monounsaturated and polyunsaturated fats. I like canola, safflower and olive oil due to their high content of these healthier fats.
Coconut oil has many other applications which are useful outside the body. It can be used as a diesel fuel, deodorant, insect repellent, to make soap, and as a moisturizer for hair and skin. My advice is to think twice however, before supplementing your diet with it.
The HCG diet has created a great deal of controversy among experts and the people who have tried it. Cami posts these words of warning about the HCG diet based on her own and her husband’s experience.
Cami writes:
What Dr. Simeons book does not tell you is that there is a good chance your hair will fall out aproximately three months after completing the 500 calorie phase of the diet. He also doesn’t mention that the shock to your system can cause adrenal fatigue, and hypothyroidism if you were already prone to these conditions.
My husband and I both went on the hCG diet and both lost the weight we had been hanging onto for years. I followed the diet perfectly, but as soon as the hCG stopped, the weight began coming back on, FAST! I had to do a steak day every other day, my blood sugar plummeted and I began to feel awful! I suffered fatigue, dry skin, dry mouth, no energy, no libido, and my muscles and joints began to hurt. The carb and sugar cravings were so intense I felt like a drug addict. I gained all the weight back plus 13 lbs. in three months, then the hair began to fall. My doctor was shocked and completely surprised. His only theory is that the usual dose wasn’t enough for me and I triggered a starvation response which affected my thyroid and adrenals. Together we are going to support adrenal health, then begin t3 therapy in an effort to repair my thyroid. My husband on the other hand, feel great! He has been able to keep off the weight, add some muscle and is happy and energetic every day. hCG does work, but if you have any health problems related in any way to the hypothalmus, I would consider taking the weight off very slowly to avoid starvation response.
It seems obvious that cutting away part of the stomach and intestine should cause weight loss. With a smaller stomach and less intestine fewer calories can be absorbed per day causing weight loss. Surgeons who perform gastric by-pass were puzzled however, by how fast their patients showed metabolic improvement after undergoing this procedure. They noticed many of their diabetic patients could be taken off diabetic medication immediately after surgery before weight had been lost. Scientists looking into this phenomena discovered unsuspected ways gastric by-pass improved metabolism.
The intestines produce hormones which regulate blood sugar and appetite. GLP-1 is among the best known of these intestinal hormones. GLP-1 is the basis of a whole new generation of medications used to treat diabetes such as Byetta, Victoza, Januvia and Onglyza. GLP-1 lowers blood sugar, stimulates the pancreas and reduces appetite. After gastric by-pass increased amounts of GLP-1 are produced by the remaining intestine. In a study published in the Journal of Clinical Endocrinology and Metabolism (95:4072-4076, 2010), researchers at St. Luke’s Hospital in New York discovered that levels of oxyntomodulin, another intestinal hormone that suppresses appetite and acts like GLP-1 on blood sugar levels, is doubled after gastric by-pass.
These exciting discoveries help explain why obese diabetics can often be sent home without any medication to control blood sugar immediately after undergoing gastric by-pass surgery. Although most insurance plans do not cover gastric by-pass surgery, dramatic improvements in patients after the procedure with greatly reduced medication costs may convince insurance companies that paying for the procedure will result in better outcomes and save them money in the long run.
A member of metabolism.com, Louise Infante, is a great enthusiast of the vegetarian life style. Louise submitted this blog to metabolism.com so we could help her get the word out. I found the article extremely informative and hope you do too. Thanks Louise for your effort.
Give me five minutes and I’ll give you 1 very good reason for being vegetarian.
While fish is the most important dietary way to obtain the long-chain omega-3s eicosapentaenoic acid and docosahexaenoic acid, which has been shown to be essential in supporting brain health, low intake of eicosapentaenoic acid and docosahexaenoic acid in vegetarians does not adversely affect mood, reported by a new study (Nutr J. 2010;9:26. DOI:10.1186/1475-2891-9-26).
A research team from Arizona State University conducted a cross-sectional study to compare the mood of vegetarians who never eat fish with the mood of healthy omnivorous adults.
An overall total of 138 healthy Seventh Day Adventist adults residing in Arizona and California (64 vegetarians and 79 non-vegetarians) were enrolled in the study and completed a health history questionnaire, food frequency questionnaire and 2 psychometric tests, the Depression Anxiety Stress Scale and also the Profile of Mood States..
Vegetarians had significantly lower mean intakes of eicosapentaenoic acid, docosahexaenoic acid and the omega-6 arachidonic acid; they had higher intakes of the omega-3 alpha-linolenic acid and the omega-6 linoleic acid.
“Seed oils are the richest sources of α-linolenic acid, notably those of rapeseed (canola), soybeans, walnuts, flaxseed (Linseed oil), clary sage seeds, perilla, chia, and hemp.”
However, the vegetarians also reported significantly less negative emotion than omnivores in both psychometric tests. Mean total psychometric scores were positively linked to the mean intakes of eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid , and inversely related to alpha-linolenic acid and linolenic acid intake.
The study team noted there is also the possibility that vegetarians may make better dietary choices and could generally be healthier and happier.
If you want to give it a try, here is an example of vegetarian recipe based on Italian cuisine
Italian Spaghetti with Zucchini
Ingredients:
* 17 oz. Spaghetti
* 24 oz. Of thin sliced zucchini
* 1 / 2 cup walnuts oil
* A few basil leaves
* 2 tablespoons of yeast flakes
* Salt and pepper
Zucchini contain fewer calories and possess no fat. But they are a good source of potassium, e vitamin, ascorbic acid, folate, lutein and zeaxanthin.
These types of nutrients are extremely sensitive to heat and to enjoy their benefits you should find a quick solution to cook or even eat raw in salads.
From the therapeutic perspective, zucchini have laxative, refreshing, anti-inflammatory, diuretic and detoxifying action.
About the Author – Louise Infante writes for vegetarian menu blog, her personal hobby blog centered on vegetarian cooking tips to help people live better.
The mission of the The Thyroid Project is to encourage sharing of information and experience between the public and the medical community about the treatment of hypothyroidism (low thyroid function). For at least the past few decades there is a growing awareness of “something missing†in the way suffers of hypothyroidism are treated for their disease.
Too many patients, as documented in an on-line study of 12,000 individuals conducted by the American Thyroid Association published in June 2018, (https://doi.org/10.1089/thy.2017.0681) , complain of persistent symptoms of hypothyroidism despite what their doctors believe is successful treatment with levothyroxine (brands include Synthroid, Unithroid, Tirosent, Levoxl). We believe something needs to be done to resolve this conflict between patients and their doctors.
Without effective intervention the early stage of type 2 diabetes known as prediabetes carries a high risk of progressing to outright diabetes. Metabolism.com provides an up-to-date summary of recommendations from national authorities, for preventing and possibly reversing this life long affliction
Diabetes can be defined simply as elevated blood sugar levels. What exactly is high blood sugar and when should someone be concerned about their level? Does having prediabetes mean diabetes is around the corner? Metabolism.com tackles this tricky but important topic in this comprehensive review.
By Gary M. Pepper, M.D. Ozempic, Rybelsus, Trulicity, Wegovy, Saxenda are the central players in the weight loss craze sweeping across the globe. Metabolisim.com has been monitoring this phenomenon from its beginnings in 2008 with its report “Lizard Spit Reduces Blood Sugar and Appetite”, regarding the first drug in this class, Byetta (exenatide). Caught In the middle of the current chaos are the medical experts who treat diabetes and have been prescribing these medications for more than a decade. Here is a brief commentary from one such board certified endocrinologist; “I started treating Type 2 diabetics with GLP-1 agonists more than 10 years ago. In some respects, these medications have revolutionized the treatment of diabetes by lowering blood sugar effectively and promoting weight loss at the same time, a unique combination of benefits. Not everyone benefits from these drugs to the same degree unfortunately, and I have seen lots of patients experience unacceptable side effects from them. Nothing though, has prepared me for what is happening now. Too often, I find myself confronting someone who expects me to prescribe one of these drugs just so they can lose weight. Sadly, one extreme example was someone who, despite battling a life threatening medical condition, was insistent on getting a prescription. At the same time my diabetic patients are scrambling to find a place to buy their medications if they can even afford it. It is disheartening, to say the least, and I dread the negative interactions with some of my patients I now face almost daily.”
Off- Label Use
The FDA is the U.S. government’s department tasked with evaluating and approving drugs for specific medical conditions. When a new medication is approved for treating a medical condition by the FDA the agency will, at the same time, set strict guidelines for exactly which patients may use the newly approved drug. When a medication is used “off-label” it means that these limitations are being overridden by the provider for a potential benefit which outweighs the drugs risks. It is a general misconception that off-label means illegal; it does not. This practice has been going on for ages and more than 20% of prescriptions in the United States are prescribed off-label. A common example is the use of beta-blockers (approved for heart problems) for the treatment of performance anxiety.
GLP-1 agonist drugs, as discussed recently by metabolism.com. were originally approved for the treatment of Type 2 diabetes in adults. In the past few years most of these same medications have gained unprecedented popularity for their “off-label” weight loss benefit. Of the 5 GLP-1 agents presently in U.S. pharmacies only Wegovy (semaglutide) and Saxenda (liraglutide) are FDA approved for treating obesity. Of these two, Wegovy is the newer and had been much more popular that its sister drug Saxenda, probably due to being dosed only once weekly compared to daily for Saxenda and less likely to cause side effects. Due to Wegovy’s soaring popularity, its manufacturer, Novo Nordisk, increased the price of Wegovy two times since its initial release.
What is Metabolism and How Does It Change with Age?
