Ever wonder why we tend to gain weight as we get older? Or why it becomes harder to lose any pounds we put on over the holidays or while on vacation? As we get older, we gain an average of one to two pounds per year.  This may not seem like a lot, but over time, it can accumulate and lead to weight gain or even obesity. Here are four major reasons why age plays a role in weight management and what to do about it:
- Muscle loss and decreased lipid turnover
- Hormonal changes
- Sedentary lifestyle
- Slower metabolism
Muscle gets replaced with fat as we age
- As we age, many of our physiological processes start to slow down—including muscle synthesis. Our muscles naturally start to break down in our 30s, after which we typically lose about 3-8% of our total body muscle per decade.  This process, known as sarcopenia, accelerates around the age of 60. Muscle loss is often replaced with fat, which requires less energy to operate than muscle. And if we don’t adjust for this decreased calorie need, then weight gain usually occurs. Scientists also recently discovered that lipid (fat) turnover rate declines with age. This rate is how fast or slow fat is removed and stored in the body. In the 2019 study, researchers followed 54 individuals over 13 years. Regardless of whether they gained or lost weight during the timeframe, all of them exhibited a slower fat turnover rate with age.
The good news is that we can actively slow down the rate of muscle loss and increase fat turnover by focusing on exercise, especially weight-bearing and resistance exercises that stimulate muscle growth. To complement muscle synthesis, make sure you meet your protein requirements. Studies show that older adults should eat slightly higher protein than the level which is recommended to preserve muscle and bone mass.  This is equal to about 1.0-1.2g of protein per kilogram of body weight each day.
As an example, a 150-pound older adult would need 68-82g of protein per day—the equivalent of a cup of lentils, two eggs, or one-3.5oz chicken breast. Focus on lean sources of protein like fish, eggs, beans, lentils, tofu, and protein shakes to meet your needs. For a complete guide to gaining muscle, check out The InsideTracker Guide to Gaining Muscle.
Hormones that help to control weight decline over timeSex hormones fluctuate with age. Estrogen levels in women drop during menopause which typically occurs between ages 45-55. Since estrogen helps regulate weight and metabolism, a decline in the hormone may lead to weight gain, typically around the midsection and abdomen. 
Other hormones like testosterone (in men) and DHEAS (in women) naturally decline over time. Testosterone drops 1-2% each year, starting around the age of 40. Testosterone helps to regulate muscle mass and fat distribution, and as it drops, the body becomes less effective at burning calories.  As with testosterone, DHEAS levels in women decline with age, starting around 20-30. Low levels of DHEAS are also linked to difficulty in controlling weight, as it's a precursor for estrogen.
You can measure your testosterone and DHEAS levels with InsideTracker. If your levels are not optimized for your age, InsideTracker provides diet, exercise, and lifestyle interventions to help you improve your levels and maximize your fitness and wellness.
Common lifestyle changes contribute to lower calorie burn and higher stressAge tends to bring along considerable life changes. The demands of a progressing career make it harder to take breaks during the workday, moving to suburbs turns a walking commute into an hour-long drive, and added responsibilities like children make it harder to get to the gym. A more sedentary lifestyle becomes the norm. With less day-to-day activity, our bodies need fewer calories. Again, adjusting to this reduced calorie requirement becomes imperative as we grow older.
Furthermore, greater responsibilities are often accompanied by increased stress. During stressful situations, the body releases a steroid hormone called cortisol. Unfortunately, sustained, elevated levels of cortisol can also lead to an increase in body fat.
To sneak in some more activity at work, use a standing desk, set up alarms on your phone to walk for 5-10 minutes every few hours, take all phone calls standing up, engage in walking meetings. At home, move around during TV commercial breaks, or incorporate dynamic stretches into your household activities. Aim to reach 10,000 steps a day. For stress-relief, try meditating daily, practicing yoga and getting enough sleep. InsideTracker also allows you to measure and track your cortisol levels to ensure optimized levels.
Our metabolism becomes slower and less efficient over timeOur metabolism dictates how many calories we need per day to accomplish bodily functions (i.e. digestion, breathing) and daily activities (i.e. physical movements, exercise). Several factors influence our metabolism including age, gender, muscle mass, hormones, stress, physical fitness level, and nutritional state. Muscle has a high metabolic rate, meaning it needs more calories to sustain itself and carry out its functions.
Since we naturally lose muscle as we age, a decrease in muscle mass also slows down our overall metabolism; as previously mentioned, less muscle means fewer calories needed. Failure to adjust our calorie intake will lead to weight gain.
To maintain a fast metabolism, focus on including at least two sessions of strength training each week, prioritize sleep to allow the body time to repair and rebuild its muscles, and sip on green tea. Green tea contains a specific compound that has been associated with an increase in energy expenditure and fat burn.  If time permits, try squeezing in a few high-intensity interval training (HIIT) workouts a few times per week. HIIT workouts increase post-exercise oxygen consumption, fat oxidation, and metabolic rate. [7-8]
A summary of age and weight maintenanceAlthough weight gain naturally tends to occur with age, fortunately, we can take action to delay or prevent the process. To recap:
- Try incorporating two to three weight-bearing exercise sessions each week to delay age-related muscle loss.
- Aim to increase your protein intake above recommended levels. Try consuming 1.0-1.2g of protein per kilogram of your body weight to help with muscle synthesis.
- Test your blood regularly to ensure healthy hormone levels.
- Incorporate daily activities such as walking, a standing desk, and dynamic stretches to avoid sitting for hours on end.
- Use meditation, yoga, and exercise to counteract stressful time periods.
- Rev your metabolism by incorporating HIIT workouts, prioritizing sleep, and sipping on green tea.
 Byrd-Bredbenner, Carol. Wardlaw's Perspectives in Nutrition. McGraw-Hill Education, 2015.
 Hursel R, Viechtbauer W, Dulloo AG, Tremblay A, Tappy L, Rumpler W, Westerterp-Plantenga MS. “The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis.” Obes Rev. 2011 Jul;12(7):e573-81.
 Chan HH, Burns SF. “Oxygen consumption, substrate oxidation, and blood pressure following sprint interval exercise.” Appl Physiol Nutr Metab. 2013 Feb;38(2):182-7.
 Wingfield HL, Smith-Ryan AE, Melvin MN, Roelofs EJ, Trexler ET, Hackney AC, Weaver MA, Ryan ED. “The acute effect of exercise modality and nutrition manipulations on post-exercise resting energy expenditure and respiratory exchange ratio in women: a randomized trial.” Sports Med Open. 2015 Jun;2. pii: 11.