Is Midlife Obesity Inevitable?

SadaNews - Some individuals blame aging and a decline in metabolic processes for their weight gain in midlife, resigning themselves to being overweight as if it were an unavoidable fate. They opt to buy new clothes instead of those that have become tight and comfort themselves with the notion that it is a part of life.

So, is weight gain in midlife truly an inevitable fate? Is a slowdown in metabolic processes the sole culprit behind weight gain?

Amidst a flood of health advice and fluctuating dietary trends, Dr. Matthias Viehwhary, a consultant in bariatric surgery at Nuffield Health in the UK, with extensive experience in metabolic issues, provides clarification on this matter for the British newspaper The Independent.

What is metabolism?

Viehwhary states, "Metabolism encompasses the chemical processes that sustain our bodily functions, from converting food into energy, repairing cells, to supporting organ functions."

The metabolic rate expresses the amount of energy the body uses to maintain these vital processes.

He adds, "Even at rest, your body is still working to maintain your heartbeat, your lungs' breathing, and your brain's activity, which is referred to as the basal metabolic rate."

Common misconceptions about metabolism

A common misconception is that metabolism alone determines body weight. Viehwhary clarifies, "Weight regulation is shaped by a complex network of factors that extend beyond just burning calories. These factors include the quality of the diet, muscle mass, sleep, physical activity, in addition to deeper physiological mechanisms such as changes in bile flow, adjustments in stomach function and size, vagus nerve signaling, and modification of gut hormones."

The gut microbiome also plays a crucial role, as it affects our efficiency in extracting energy from food, how we process bile acids, and how our metabolism functions overall.

Some people assume that metabolism steadily decreases after early adulthood, but this is inaccurate. Viehwhary explains, "Large-scale, high-quality studies show that it remains remarkably stable for decades before gradually slowing down later in life."

How does metabolism change with aging?

Viehwhary states, "Metabolism is not a straight decline. A significant study published in Science in 2021, which included more than 6,000 people, showed that energy expenditure peaks in childhood - where it can be 50% higher than in adults - and then gradually declines until approximately the age of twenty."

The metabolic rate remains remarkably stable when adjusted for body size and composition from the twenties until around sixty. After sixty, the metabolic rate tends to decrease slowly, but it is measurable.

What are the reasons for this decline from age sixty and above?

Viehwhary notes, "After sixty, the metabolic rate typically decreases by about 0.7% annually. The main reasons are loss of muscle mass, decreased physical activity, and slight hormonal changes such as declines in growth hormone and sex hormones."

Mitochondrial efficiency - the body's energy production mechanism - may also decline slightly with age. This does not mean the body forgets how to burn energy, but rather it becomes less efficient at it.

What lifestyle factors influence metabolism?

Many lifestyle habits can support or slow down metabolic function.

Loss of muscle mass or inactivity

Viehwhary explains, "Muscle tissue burns more energy than fat, even at rest."

Following a strict diet

He clarifies, "Severely restricting caloric intake can temporarily inhibit metabolic rate."

Lack of sleep

Viehwhary points out that "Lack of sleep can affect hunger and energy-regulating hormones such as leptin and ghrelin."

Chronic stress

He states, "Elevated cortisol can promote fat storage and affect energy usage."

Source: Independent