Decoding Weight Gain After 30: It's Not Just About Metabolism

Entering our 30s often comes with surprises, including changes in our bodies that we might not have expected. One common concern is weight gain, often attributed to a slowing metabolism. However recent research challenges this idea.

In this blog post, we'll explore why weight gain after 30 isn't solely about metabolism. Instead, we'll uncover the real reasons behind those extra pounds as we navigate this stage of life. Let's dive in and discover the truth together.

First, let´s look at what exactly metabolism is. Metabolism is how our bodies turn food into energy to keep us alive. It includes everything from breathing and blood circulation to digesting food and getting rid of waste.

The minimum energy needed for basic body functions when resting and fasting is called the basal metabolic rate (BMR). It can be figured out using online calculators based on factors like height, weight, age, and sex.

BMR is also known as resting metabolic rate (RMR). Total energy expenditure (TEE) includes BMR, energy for physical activities, and energy used for digesting food (called dietary thermogenesis). For less active adults, BMR makes up about half to two-thirds of total energy use, dietary thermogenesis about 10% to 15%, and physical activity the rest, around 20% to 30%.

WHAT DOES SCIENCE SAY ABOUT MIDDLE AGE METABOLISM

The concept of metabolism slowing down as we age has been challenged by a groundbreaking study conducted by Pontzer et al. (2021). This longitudinal study, which observed over 6,400 individuals from infancy to 95 years old, aimed to determine whether metabolic rates decrease after early adulthood.

Taking into account variations in body size and composition, the researchers found some unexpected results. Infants under the age of 1 exhibited metabolic rates around 50 percent higher than adults when adjusted for body size. Energy expenditure appeared to decline until around the age of 20, stabilizing until approximately 60 years old, after which a gradual decline was observed into older adulthood.

Pontzer et al. (2021)

During adulthood, from around 20 to 60 years old, the total energy expenditure, basal expenditure, and fat-free mass remained steady regardless of gender. Both adjusted total energy expenditure (TEE) and resting metabolic rate (RMR) stayed consistent even during pregnancy. Any rise in energy expenditure during pregnancy was due to the increase in body weight. The decline in adjusted TEE began at approximately age 63, while adjusted basal metabolic rate (BMR) started to decrease around age 46.5, although the researchers noted a limited number of BMR measurements, which affected their confidence in this estimate.

These findings challenge the notion that weight gain in middle age is primarily attributed to a decrease in metabolism. Instead, the study suggests that behavioral factors such as diet and exercise habits play a more significant role in weight management during this stage of life.

WHY WE GAIN WEIGHT AFTER OUR 20S: WHAT WE KNOW

It's often believed that our metabolism slows down as we hit our thirties due to aging, but the truth is far from clear-cut. Let's break down what we do understand.

THE DECLINE IN SKELETAL MUSCLE MASS

Skeletal muscle plays a crucial role in our metabolic health. It's a metabolically active tissue, meaning it burns calories just by existing. Plus, it interacts with other parts of our body by releasing various compounds. Skeletal muscle helps regulate glucose levels by absorbing circulating glucose, essentially acting as a storage spot instead of letting it turn into fat.

Some formulas for predicting resting metabolic rate, like the Katch-McCardle formula, rely on how much lean body mass someone has, not just their weight. Generally, the more skeletal muscle you have, the higher your resting metabolic rate, which is why strength training is beneficial for weight loss.

In our younger years, muscle cells respond well to exercise, but as we age, they become less responsive. It's well-known that after 30, we tend to lose some muscle mass—about 3 to 8 percent every decade. This could be due to lifestyle changes, like more sedentary jobs and less time for workouts, but the declining response of muscle cells also plays a role. With less muscle mass, our resting metabolic rate decreases, making weight gain more likely even if our eating habits haven't changed.

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THE DECLINE IN REPRODUCTIVE HORMONE LEVELS

Hormones like estrogen, progesterone, and testosterone start to decline gradually after our twenties. While men usually maintain normal testosterone levels into older age, it still decreases about 1-3 percent per year.

Women also experience a drop in hormone levels, with estrogen and progesterone becoming less reliable, especially around 40 years old. Human growth hormone, essential for muscle and bone health, also declines, contributing to increased fat and decreased metabolism.

CHANGES IN PHYSICAL ACTIVITY

Staying physically active as we age is crucial for maintaining a healthy weight. Unfortunately, busy schedules and declining physical fitness can make it harder to stay active. Studies show that physical activity tends to peak in early adulthood and then steadily declines from the thirties onward. This decrease in activity directly relates to weight gain, as we burn fewer calories overall, both at rest and during physical activity.

IT IS ABOUT OUR BEHAVIORS

The thing is, when we are in our 30s, we have more responsibilities and comfort at the same time. You are more likely to use a car, to save time, rather than walk or take a bus. We focus on our careers and are more likely to eat out, instead of cooking at home.

So making healthy lifestyle choices, like eating well, staying active, and getting enough sleep, can help prevent weight gain as we age. Here is what we can do:

SETTING REALISTIC WEIGHT GOALS

When setting weight goals, it's essential to be realistic. Not everyone can achieve a super-lean physique, and that's okay. Instead of aiming for a specific number on the scale, focus on finding a weight that feels good and can be maintained with healthy habits.

BALANCED DIET

A balanced diet is key. Include all food groups, enough fiber, limit saturated fats, and get plenty of protein to build and maintain muscle mass. For weight loss, aim for a moderate calorie deficit, around 150-300 calories per day, and focus on whole grains, fruits, and vegetables for carbs.

To estimate calorie needs accurately, keep a food diary and use a food logging app. This helps you understand your energy needs and decide on a suitable calorie deficit for weight loss. Our 6-week gym workout plan also includes comprehensive guidance in nutrition and a balanced diet.

A SUSTAINABLE FITNESS ROUTINE

Being physically active is crucial for maintaining a healthy weight. Aim for 150 to 300 minutes of moderate or 75-150 minutes of vigorous activity per week, including resistance training twice a week.

For many middle-aged adults, aiming for 10,000 to 12,000 steps a day and doing resistance training 2 to 3 times a week works well. Remember, steps are just one way to measure activity, so find activities you enjoy to stay active and healthy.

In conclusion, maintaining a healthy weight after 30 involves a combination of factors, with diet and exercise playing pivotal roles. And it is not the metabolism´s fault. While there's no one-size-fits-all approach, setting sustainable weight goals, following a balanced diet, and incorporating regular physical activity are essential steps toward achieving and maintaining a healthy weight.

By understanding the importance of realistic weight goals, balanced nutrition, and consistent exercise, individuals can take proactive steps to mitigate middle-aged weight gain and promote overall health and well-being. Remember, it's not just about looking a certain way; it's about feeling your best and supporting your body with healthy habits that you can maintain for the long term.

So, whether you're embarking on a weight loss journey or simply aiming to maintain your current weight, prioritize sustainable lifestyle changes that align with your individual needs and preferences. With dedication, patience, and a focus on overall health, achieving and maintaining a healthy weight after 30 is within reach for everyone.

DISCLAIMER

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.