Why most people start gaining weight in their 20s

Eating a balanced diet and getting sufficient exercise are crucial to maintain a healthy weight. (Thinkstock photo)
Eating a balanced diet and getting sufficient exercise are crucial to maintain a healthy weight. (Thinkstock photo)

Weight gain is common as we age. As you move through your 20s on to your 30s, you may notice subtle changes in your waistline, and an increasing tendency to gain weight.

Many attribute age-related weight gain to a slowing metabolism. Slow metabolism however is rare, and it’s usually not what’s behind being overweight or obese. Rather than slow metabolism, factors more likely to contribute to weight gain with ageing include:

  1. Overconsumption of calories

  2. Physical inactivity

  3. Genetics and family history

  4. Certain medications

  5. Unhealthy lifestyle habits such as skipping breakfast or not getting enough sleep

We should however be mindful that metabolic rate does change as we get older because of the decline in our muscle mass. This reduction in muscle mass begins relatively early at the age 35, becomes more profound with time and continues until the end of our life.

Since our resting metabolic rate is dependent on our body composition – muscle being more metabolically active and burning more calories than fat – the change in body composition with ageing (less muscle and more fat) means that less calories are required to maintain the same body weight.

Related article: Boost your metabolism and speed up weight loss

How many calories to maintain your weight

The body receives energy in the form of calories from food. Generally, to maintain your weight, you need to burn all the calories you consume. If you want to lose weight, you must burn more calories than you consume. Any unburned calories end up as fat in the body. Examples:

If you are a woman in your 20s, weigh 55kg, and hold a sedentary job, the recommended energy allowance is:

  • 1750 kcal (light activity)

  • 1950 kcal (moderate activity)

  • 2050 kcal (vigorous activity)

If you are a man in your 20s, weigh 60kg, and hold a sedentary job, the recommended energy allowance is:

  • 2100 kcal (light activity)

  • 2300 kcal (moderate activity)

  • 2600 kcal (vigorous activity)

Related article: 8 tips to lose weight healthily without dieting

A balanced diet and physical exercise in your 20s

No matter at what age, your focus should be on eating a balanced, nutrient-rich diet and getting enough physical exercise to maintain a healthy weight and build bone density. This way you protect yourself from developing chronic health conditions like high blood pressure, high cholesterol, heart disease, diabetes and osteoporosis.

Although lifestyle diseases such as atherosclerosis (thickening and hardening of the arteries) manifest later in life, the disease process starts years before. Hence there is a need to build good habits from early adulthood.

“You should always focus on disease prevention rather than cure. It is important to do regular physical exercise that includes aerobic and weight-bearing exercises,” says Dr Tan Hong Chang, Associate Consultant, LIFE Centre, Singapore General Hospital (SGH). Weight-bearing exercises like walking and jogging, work your bones against gravity and make them stronger. These should be done for 30 minutes, at least twice a week.

Unfortunately, many people in their 20s, particularly women, prefer to go on fad diets instead of going for a walk or working out in the gym.

“Many go on crash diets which have a counter-productive effect. Results may only be short lived and not sustainable in the long-term,” says Dr Tan.

Related article: In your 30s? Here’s how you can be in your best shape

This article was written by Anjana Motihar Chandra for Health Xchange, with expert input from the LIFE Centre, Singapore General Hospital (SGH).

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Health Xchange's articles are meant for informational purposes only and cannot replace professional surgical, medical or health advice, examination, diagnosis, or treatment.