Why Some People Really Struggle to Lose Weight More Than Others

"Fat people just need more self-control." "It’s about personal responsibility." "It’s simple, just eat less." These were just a fraction of the 1,946 comments posted beneath a recent article about weight-loss injections, highlighting a pervasive, yet increasingly challenged, belief: that obesity is solely a matter of willpower. A study revealed that a staggering eight out of 10 people surveyed in the UK, Australia, New Zealand, and the US believed obesity could be entirely prevented by lifestyle choices alone. However, this simplistic view is met with exasperation by health professionals like Bini Suresh, a dietitian with two decades of experience working with obese and overweight individuals. "I frequently see patients who are highly motivated, knowledgeable, and trying consistently yet still struggling with weight," she states. Dr. Kim Boyd, medical director at WeightWatchers, echoes this sentiment, asserting that terms like "willpower" and "self-control" are misleading. "For decades people have been told to eat less and move more and they will lose weight… [But] obesity is much more complex." Experts now understand that a multitude of factors, some still not fully understood, contribute to obesity, creating an uneven playing field for weight management.

In an attempt to address this complex issue, the government has implemented regulatory measures, such as the recent ban on junk food advertising on television before 9 pm and a complete prohibition on online promotions of such products. Yet, many believe these measures will only offer a partial solution to the escalating obesity crisis in the UK, where over one in four adults are now classified as overweight or obese.

A Battle Against Biology

Professor Sadaf Farooqi, a consultant endocrinologist and leader of the Genetics of Obesity Study at Cambridge University, emphasizes the significant influence of genetics on weight gain. "The amount of weight people gain is significantly influenced by their genes, and those genes are relevant for everybody," she explains. These genes impact brain pathways that regulate hunger and satiety, meaning individuals with certain genetic variations may experience increased hunger and a reduced feeling of fullness. "Variants or changes in these genes are found in people with obesity, which means they feel more hungry and are less likely to feel full after eating." Professor Farooqi further notes that other genes influence metabolism, affecting how quickly individuals burn energy. "That means some will gain more weight and store fat from eating the same amount of food, than other people do, or they will burn less calories when they exercise." She estimates that thousands of genes likely influence weight, with detailed knowledge currently limited to around 30 to 40. This understanding is crucial, she believes, in explaining the effectiveness of emerging weight-loss drugs, which target these biological mechanisms.

The Science Behind Yo-Yo Dieting

Beyond genetics, the concept of "set weight point theory" offers another layer of explanation for weight management challenges. Andrew Jenkinson, a bariatric surgeon and author, explains that our brains operate with a perceived "set weight," which is influenced by genetics, our food environment, stress levels, and sleep quality. This set point functions much like a thermostat; if weight drops below this range, hunger increases, and metabolism slows down. Attempting to alter this set point through willpower alone is exceptionally difficult, according to Dr. Jenkinson. This theory also sheds light on "yo-yo dieting." When an individual loses weight below their set point, their body responds as if starving, triggering intense hunger and a drive to regain weight. "It’s going to have that reaction of voracious appetite, food-seeking behaviour and a low metabolism," he warns. "These appetite signals are profoundly strong. They’re as strong as a thirst signal, they’re there to help us survive… A voracious appetite is something that’s really, really difficult to ignore."

The hormone leptin, produced by fat cells, plays a critical role in this process. Leptin signals to the hypothalamus, the brain region controlling our weight set point, about the body’s energy stores. Ideally, if leptin levels indicate excess fat, the hypothalamus should reduce appetite and increase metabolism. However, this signaling pathway can be disrupted, particularly in environments that promote overconsumption. Dr. Jenkinson explains that leptin shares a pathway with insulin, and high insulin levels can dilute the leptin signal, preventing the brain from accurately sensing stored fat. While the set point isn’t immutable, it can be gradually shifted through sustained lifestyle changes, including improved sleep, stress reduction, and consistent healthy habits.

Obesity in the UK: The Perfect Storm

The rise in obesity rates cannot be attributed to changes in our genes, as they have remained constant. Instead, external factors have created an "obesogenic environment." The proportion of adults classified as overweight or obese in the UK has steadily increased, with projections indicating over 60% of adults falling into this category by 2025, including approximately 28% who are obese. This surge is fueled by the widespread availability and affordability of poor-quality, high-calorie foods, particularly ultra-processed items. Aggressive marketing of fast food and sugary drinks, increasing portion sizes, and limited opportunities for physical activity due to urban design and time constraints contribute to a perfect storm. Public health experts refer to this phenomenon as the obesogenic environment, a concept that emerged in the 1990s as researchers began linking rising obesity to external influences. These combined factors create constant pressures towards overeating and inactivity, making it challenging for even the most motivated individuals to maintain a healthy weight.

The Personal Responsibility Debate

Alice Wiseman, public health director for Newcastle City Council, observes the pervasive presence of food outlets, stating, "There are coffee shops, bakeries and takeaways. You can’t go to school or work without passing a food place." This constant visibility, she argues, influences our choices. In Gateshead, a deliberate policy has been in place since 2015 to refuse planning permission for new hot food takeaways. However, the fast-food and takeaway industry continues to thrive nationwide, generating over £23 billion annually. Advertising spend in the UK is heavily dominated by products high in fat, salt, and sugar, according to Ofcom reports. While acknowledging the role of personal responsibility, Ms. Wiseman questions what has changed fundamentally in our willpower, suggesting the environment is now engineered for over-consumption. She asserts, "Obesity is not a failure of character. It’s a complex, chronic condition shaped by biology and a highly obesogenic environment. Willpower alone is not enough and framing weight loss as solely a matter of discipline does harm."

Conversely, Professor Keith Frayn, author of "A Calorie is a Calorie," agrees that the environment has shifted significantly over the past 40 years, making it more challenging to maintain a healthy weight. However, he cautions against dismissing "willpower" entirely, as it could lead to resignation and hinder individuals from pursuing desired health outcomes. He points to the National Weight Control Registry in the USA, comprising over 10,000 individuals who have successfully lost and maintained weight, many of whom describe the process as "hard." He believes these individuals would find the notion that willpower plays no role quite offensive.

‘You Can’t Legislate People into Shape’

The debate over governmental responsibility in tackling obesity is multifaceted. Ms. Wiseman advocates for regulation, citing how promotions like "buy-one-get-one-free" can encourage impulsive purchases. However, Gareth Lyon, head of health and social care at Policy Exchange, argues that further legislation is not the solution, stating, "You can’t legislate people into shape." He believes that bans and taxes on enjoyable foods make life more difficult and expensive for individuals already grappling with the cost of living. Christopher Snowdon, head of lifestyle economics at the Institute of Economic Affairs, views obesity as an "individual problem" stemming from personal choices, not a public health crisis. He questions the government’s role in dictating individuals’ weight and calls for independent evaluations of policies, advocating for their repeal if ineffective.

The role of willpower remains a subject of debate, with experts differing on its extent of influence. Ms. Suresh believes it is one component of a larger picture, emphasizing the importance of educating individuals about the myriad factors at play. This shift, she suggests, moves away from moral judgment towards a compassionate, science-informed approach that offers greater potential for long-term success. Dr. Eleanor Bryant, a psychologist at Bradford University, suggests that willpower is not a constant attribute but is influenced by mood, fatigue, and hunger. She distinguishes between "rigid" and "flexible" willpower, with the latter proving more successful. A flexible approach allows individuals to acknowledge a lapse (e.g., eating a biscuit) and then stop, whereas a rigid approach can lead to disinhibited eating. Dr. Bryant acknowledges that exercising willpower with food is likely more challenging than in other life domains. Ms. Suresh concurs, noting that understanding the biological limitations of willpower can paradoxically strengthen an individual’s ability to manage it. When individuals grasp that their struggles are rooted in biology rather than a lack of discipline, and receive support through structured nutrition, consistent meal patterns, psychological strategies, and realistic goals, their relationship with food often improves significantly.