The surprising reason behind yo-yo weight loss.

Many American adults struggle with weight fluctuations, as obesity affects about 40% of them.

A new study suggests that the yo-yo effect, which involves repeatedly losing and regaining weight, may be caused by a type of "metabolic memory" where the body remembers and strives to return to its former state of obesity.

Dr. Ferdinand von Meyenn, an assistant professor for nutrition and metabolic epigenetics at ETH Zurich in Switzerland, stated that obesity is a chronic condition with significant metabolic consequences, strongly linked to various metabolic and cardiovascular diseases, according to a study he authored.

"It is commonly observed that the body resists weight loss and maintenance due to its tendency to defend increased body weight."

One in five children and two out of five adults in the U.S. suffer from obesity, as per the Centers for Disease Control and Prevention (CDC).

The study published in Nature in November suggests that epigenetics, or genetic activity, may contribute to regaining weight after losing it.

What is epigenetics?

According to Dr. Fatima Cody Stanford, an obesity medicine physician at Massachusetts General Hospital and Harvard Medical School, epigenetics, which involves chemical markers that affect gene activity without changing the DNA sequence, is essential for how cells function and respond to environmental factors.

Stanford stated that these markers can be modified by lifestyle factors, such as diet, and can remain unchanged for years, resulting in a cellular "memory" of past conditions, including obesity.

Von Meyenn stated that researchers were curious about the fate of fat cells, which have an average lifespan of 10 years and are replaced by the body.

Intestinal cells typically divide every other week, unlike other cells in tissues that divide much faster.

Von Meyenn pointed out that fat cells must adapt to external stimuli and undergo epigenetic changes.

The researchers set out to determine whether these changes could be reversed.

Fighting ‘memory’ in fat cells

Even after significant weight loss, the cells of mice have a "memory" of obesity encoded in the epigenome, which controls the activity of genes, according to von Meyenn.

One reason maintaining body weight after initial weight loss is difficult is that fat cells remember their prior obese state and likely aim to return to this state, according to a study.

"The body tends to defend increased body weight, making weight loss and maintenance notoriously challenging."

"To maintain body weight, one must "battle" this obesogenic memory."

According to von Meyenn, the inability to sustain weight loss after dieting may not be solely due to a lack of effort or willpower, but could also be influenced by a biological factor.

Potential limitations

Although the study focused solely on fatty tissue in mice and did not examine genetic mechanisms in humans, the researchers asserted that similar mechanisms likely exist in humans.

While other experts warned that the study only shows an association and does not prove that epigenetic changes cause the yo-yo effect.

According to Petronella Ravenshear, a board-certified nutritionist and author of "The Human Being Diet," the authors of the study cannot definitively say that epigenetic modifications directly cause people to lose weight, nor can they identify which specific epigenetic markers may be responsible for this effect.

Ravenshear, a Florida-based researcher not involved in the study, cautioned against using the results to assert, "It’s not my fault, it’s my genes!"

Plans for future research

Von Meyenn stated, "Now we must expand our investigation to determine if memory can be erased and if other cells or tissues, such as the brain or liver, are also affected."

According to Ravenshear, maintaining a healthy weight for a year or more after dieting may be sufficient to eliminate the memory stored in fat cells.

Stanford emphasized the significance of preventing obesity in children and adolescents to avoid the establishment of an epigenetic memory that makes long-term weight management difficult.

She emphasized the importance of a proactive approach to weight management from an early age, stating that further understanding of these mechanisms could lead to more effective treatments and prevention strategies.

‘Way of living’

Ravenshear pointed out that while "diet" originally referred to a long-term way of living, it now typically refers to short-term, unsustainable changes.

Experts concur that individuals frequently regain the weight they shed when they revert to the eating habits that caused weight gain initially.

Professor David Benton of Swansea University in the U.K., author of "Tackling the Obesity Crisis," stated in a Guardian interview that "The mantra is that diets fail."

"To permanently avoid regaining lost weight, you must change your diet."

Many individuals revert to their prior unhealthy habits after completing a diet, according to him.

Eating calorie-dense, nutrient-poor foods frequently disrupts our blood sugar, raises insulin levels, and inflammation, making it harder to lose weight, according to Ravenshear, who spoke to Planet Chronicle Digital.

Breaking addictions to sugar and refined carbohydrates is recommended, along with adopting a new eating style.

The expert recommends consuming whole foods rich in nutrients, eating three meals daily, and fasting for five hours straight with only water in between meals.

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She observed that weight loss is a consequence of hormonal balance and reduced inflammation.

Ravenshear stated, "Our brain drives us to keep searching for food when we are not getting the necessary nutrients along with calories."