The physiology of weight loss and maintenance

Obesity is a serious global health issue, and it has long been thought to be caused by self-inflicted unhealthy behaviors. Human body weight regulation is influenced by a variety of systems, including genetic, physiological, and behavioral factors.

The American Medical Association didn't declare obesity "a disease needing a range of medical approaches to enhance obesity treatment and prevention" until 2013. Although dietary changes and increased physical activity are both rational and safe weight-reduction therapies, they are frequently insufficient to sustain long-term weight loss maintenance. Many people regain weight that they had previously lost over time.

Weight reduction is complicated by a number of factors that make it more difficult to attain and maintain.

Hormones

A complicated neuro-hormonal system controls body weight. Hormones and the brain are both engaged. The hypothalamus, in particular, has a role in weight control. Hormonal signals from the gastrointestinal system, pancreas, and adipose tissue are received by this portion of the brain.

Hormones can influence hunger. Our bodies produce orexigenic hormones, which cause us to acquire weight. Ghrelin, also known as the "hunger hormone," is an example. Ghrelin promotes fat accumulation and enhances appetite.

Anorexigenic hormones, which cause weight loss, are also found in our bodies. Leptin is an anorexigenic hormone that suppresses hunger and so reduces fat storage.

Following a successful weight loss, hormonal changes may occur. These modifications have been shown to promote weight gain by raising hunger and encouraging fat storage. Ghrelin levels have been found to be higher while leptin levels have been shown to be lower. Furthermore, one research of fifty overweight and obese people revealed that this major hormonal imbalance was still present one year after they had lost weight on a diet. This indicates that the change in appetite-controlling hormones is not temporary.

Thermogenesis is reduced.

Adaptive thermogenesis has been discovered as a result of weight loss. Significant weight loss or food scarcity might drive the body to prioritize energy conservation by lowering energy expenditure. The "starvation response" is another name for it. This survival mechanism is meant to keep you from starving, but it also makes losing weight more difficult.

You may be familiar with the reality show "The Biggest Loser." This tournament had about 15 contestants who were studied. Their resting metabolic rate was determined to be roughly 500 calories per day lower than expected based on their body composition. Additionally, those who lost the most weight saw the greatest slowdown of their resting metabolic rate.

Environment that promotes obesity

Obesogenic means "having the potential to promote obesity." Overindulgence is possible in our current atmosphere. High-calorie foods are heavily promoted, and portion sizes are growing. The obesity pandemic is exacerbated by the increased availability and low cost of these energy-dense dietary options.

Stress plays a role as well. Compensatory food consumption can be stimulated by living in a fast-paced, high-stress society. Our current environment makes it even more difficult for people to maintain a healthy body weight through well-balanced nutrition and physical activity, particularly if they work in a sedentary atmosphere.

Stress

The main stress hormone in the body is cortisol. It not only fuels our "fight or flight" reaction, but it also regulates blood pressure, raises blood sugar, and controls how carbohydrates, fat, and protein are used by the body. Cortisol is necessary for human health, but too much of it can cause weight gain by increasing appetite and encouraging overeating. It might be tough to maintain healthy eating habits when you are under a lot of stress. For comfort, some people turn to high-calorie, decadent foods.

The 24-hour clock

The body's 24-hour clock, which governs the sleep/wake cycle in reaction to light and darkness, is known as the circadian rhythm. According to some studies, eating late at night or outside of usual meal times can disrupt this cycle. In addition, studies have found a link between obesity and sleep deprivation. Metabolic dysfunction, changes in eating behavior, and weight gain have all been linked to circadian disruption.

Obesity medicine and bariatric surgery

Because compensatory physiological adaptations favor weight recovery, resetting an individual's physiology may be the most effective strategy to support long-term weight loss. Anti-obesity drugs, as well as bariatric surgery, may be useful in this regard. According to some study, these weight-loss methods have the best long-term success.

Gastric bypass surgery, for example, has been reported to cause "deep physiological and metabolic alterations" as a result of surgical manipulation. Bariatric surgery has had remarkable positive clinical effects.

Weight loss drugs are also on the horizon, and some people are already taking them. Obesity is being recognized as an illness in the same way that diabetes and hypertension are. When a person is diagnosed with diabetes, a doctor will usually prescribe medication to assist lower blood sugar levels. Obesity, like diabetes, is a disease having physiological components. Obese people, like diabetics, should make dietary and behavioral modifications. Perhaps, in the future, practitioners will be more likely to consider drugs to treat obesity as well.

Conclusion

In 2020, the adult obesity rate in the United States was 42.4 percent. Obesity has roughly tripled globally since 1975. This disease not only lowers quality of life, but it also puts people at risk for various health problems like type 2 diabetes, heart disease, stroke, cancer, and arthritis. Obesity is associated with a reduction in life expectancy.

According to a peer-reviewed article released by the American Diabetes Association in 2017, genetics account for around half of weight variation, while environmental variables such as decreased physical activity and the consumption of high-calorie meals account for the other half. Hormonal, metabolic, and neurological processes all play a role in weight regain and have been linked to it. Our medical field will hopefully be able to design more effective techniques to support long-term weight loss as our understanding of the physiology of weight regulation improves.