Maintaining an ideal weight is hard. It takes discipline. It takes dedication. It takes a lot of hard work. And that’s when you’re young.
Unfortunately, it gets even harder with age. By the time you’re blowing out 40 candles on your birthday, biology begins working against your weight loss efforts.
In this article, we’re going to discuss some of the features of aging that make weight loss more difficult. This is Part 1 of a 2 part series that will tell you why weight loss gets harder with age. Part 2 will cover some simple tweaks you can make to your diet and exercise routine that make weight loss over forty possible.
1) The older you are, the slower your metabolism gets
Your metabolism is the sum of all the life-sustaining chemical reactions that occur inside your body. These include the reactions that convert food to energy or building blocks for macromolecules (proteins, lipids, and nucleic acids) and those that lead to the elimination of nitrogenous wastes, which is vital for survival.
In ever day language, the word metabolism is often used as a synonym for metabolic rate, which is the amount of energy used in a given period of time. A day, for example. Metabolic rate is measured in calories. Your basal metabolic rate is the amount of energy your body uses at rest.
Basal metabolic rate decreases with age by approximately 5% every ten years after 40. If your resting metabolic rate is 1,200 calories per day when you are 40, your resting metabolic rate when your 50 would be about 1,140 calories per day. At 60, your resting metabolic rate would be approximately 1,000 calories per day.
A decreasing basal metabolic rate with age means you could start eating a surplus of calories on a daily basis without any change in your eating habits or activity levels. This could lead to unwanted weight gain. For example, if your average daily intake of calories from your diet was 1,700 calories when you’re 40, you would have a 500 calorie surplus to be used as energy to fuel bodily functions and activities. Eating the same number of daily calories when you’re 50, results in a 560 calorie surplus. When you’re 60, that’s a calorie surplus of 700.
|Age||Basal Metabolic Rate||Calorie Surplus|
Based on a daily intake of 1700 calories and a basal metabolic rate of 1,200 at age 40.
2) You lose lean muscle mass with age.
As you get older, muscles decrease in size, muscle fibers begin getting replaced by fat, muscle tissue becomes more fibrotic, muscle metabolism changes, oxidative stress increases, and the neuromuscular junction degenerates. The medical term to describe these changes is sarcopenia.
Sarcopenia occurs at a rate of approximately 0.5-1% per year after the age of 50. Sarcopenia has a significant impact on weight loss with age because lean muscle drives metabolism. The more lean muscle you have the higher your resting metabolic rate is going to be. The higher your resting metabolic rate is, the more calories you’re going to burn and the easier it’s going to be to lose weight.
Sarcopenia is just one of the factors contributing to a slowing metabolism with age.
3) Hormones change with age
For men, testosterone drops as you age. Testosterone is a steroid hormone. When you’re young it plays a key role in the development of the male reproductive organs and promotes secondary sexual characteristics like increased bone and muscle mass and the growth of body hair. After puberty and into adulthood, testosterone is necessary for sperm development, it regulates the HPA (hypothalamic-pituitary-adrenal) axis, and it enhances muscle growth.
Decreasing testosterone levels with age in men contribute to decreasing lean muscle mass – which impacts metabolism – and less of a drive be active. Both of these factors can make weight loss more difficult for men in the later decades of life.
For women, with age comes menopause. With menopause comes changes in three hormones: estrogen, progesterone, and testosterone.
Estrogen falls to a very low level after menopause. Low levels of this hormone are associated with hot flashes, night sweats, palpitations, headaches, insomnia, fatigue, bone loss, and vaginal dryness – many of the symptoms generally thought of during menopause.
Progesterone production stops after menopause and testosterone levels fall.
Changes in estrogen, progesterone, and testosterone have profound effects on the rest of the endocrine system. After the menopause the entire hormone environment is changed. These changes affect metabolism, sleep, and activity, which all impact the ability to lose weight.
4) The consequences of bad eating habits are more pronounced
Life tends to be busier and more active when you’re young. Think about everything you did in high school: gym class during the day, extracurricular sports in the evening, walk home, walk around the mall. You were always moving.
Your twenties weren’t much different. You chase a career to a big city where walking or biking is easier than driving, you take a low paying job that requires you to run around like a chicken on cocaine, and you spend the weekends “out.” Kids may have even appeared in this decade, which makes you reconsider ever having thought you were busy before.
A busy lifestyle when you’re young and have a fresh off the car lot, new car metabolism allows you to get away with a lot. You can eat an entire pizza at 2:00 a.m. You can eat ice cream whenever you crave it. A carb heavy pasta dish isn’t going to affect you at all. And, when you want to lose weight, just about any diet works.
When middle age begins to appear on the horizon, you start slowing down. Weekends are spent with a martini on the porch visiting with your neighbour; you get promoted to a desk job where people are doing the running around for you, and you can afford that nice car and the parking spot downtown that allows you to drive to work.
Because of decreased activity, slower metabolism, sarcopenia, and hormone changes with age, little things in your diet that could be overcome when you were young start to matter once you hit 40. In middle-age, everything – good and bad – starts to count.
A slower metabolism, lean muscle loss, hormonal changes, and bad eating habits are the main reasons losing weight after 40 is difficult. But difficult doesn’t mean impossible. Next week, we’re going to cover exercise and dietary changes you can use to lose weight at any age.
Sources and further reading