Many individuals have attempted to trim their waistlines through calorie counting and frequent gym visits, yet often with little success. So, what’s the underlying issue?

According to Dr. Andrew Jenkinson, a consultant in bariatric surgery at University College London Hospital and author of Why We Eat (Too Much) and How to Eat (and Still Lose Weight), losing weight is less about the quantity of food consumed or the amount of exercise than previously thought.

He suggests that rather than obsessing over calorie counts and relentless gym sessions, a more practical approach to weight loss could be achieved by consuming foods that effectively regulate levels of the hormone leptin.

How does leptin function? What foods should fill your plate? Is there a straightforward way to combat cravings? Dr. Jenkinson addressed these topics in detail during our recent discussion.

BBC Science Focus: What is the global obesity crisis?

AJ: The Western world faces significant issues that are straining healthcare systems. In the U.S., about one-third of the population is considered morbidly obese, impacting their health drastically.

In Europe, the rate is around one-quarter. Many of these individuals face heightened risks of type 2 diabetes, hypertension, sleep apnea, joint problems, and certain cancers.

For the first time in history, life expectancy is declining due to obesity. New treatments, such as injections, are available, but they come at a hefty price.

Millions rely on them, and thus, obesity has become a major economic and health concern that requires urgent attention.

Obesity does not stem solely from the abundance of appealing, high-calorie food. These foods may act similarly to drugs, disrupting normal weight regulation mechanisms.

Wild animal populations face similar biological pathways, yet there’s no evidence that lions become inactive due to an oversupply of antelope.

Is the issue rooted in our hormones?

Yes. Leptin, often termed the ‘satiety hormone,’ is crucial in regulating the weight of wildlife and should ideally function in the same way for humans.

Leptin levels send signals to the brain’s weight control center, located in the hypothalamus. This hormone essentially dictates body weight: when leptin is detected, appetite diminishes and metabolism increases.

Leptin is produced by fat cells, meaning that higher leptin levels should correlate with reduced appetite and increased metabolism.

However, some food types can obstruct leptin signaling. While it’s well-known that sugar, refined carbohydrates, and processed foods contribute to obesity, the root cause isn’t merely their calorie content; it’s how they elevate insulin levels, which in turn inhibits leptin.

When leptin signaling fails, the brain loses track of whether we are overweight or underweight. You might look visibly overweight, but your brain might mistakenly signal that you need to eat more.

It’s akin to driving a vehicle and suddenly noticing the fuel gauge is empty. You panic and refuel, but the tank was never really empty to begin with—the gauge itself was faulty. Similarly, when leptin is blocked, your body undergoes a comparable malfunction.

What significance do calories hold for weight loss?

Calories are essential for survival, acting as energy units stored within plants. Plants predominantly store carbohydrates and energy within their cellular structures.

We utilize this energy for various bodily functions like heat generation, heartbeat, and movement. Interestingly, approximately 70% of the energy we consume is expended at rest, termed basal metabolism, which encompasses immune functions, maintaining body temperature, heart rate, and more.

There’s a common misconception among those who focus exclusively on calorie counts: the body can easily eliminate excess calories. For instance, you could adjust basal metabolism to burn an additional 600-700 calories daily through activity akin to enjoying a lavish three-course meal or engaging in a 10k run.

If you adopt a low-calorie diet, your body can also adapt to this lower intake, ultimately halting weight loss within weeks.

Moreover, while many individuals may overconsume, our bodies respond by increasing basal metabolism, leading to greater energy expenditure. This is a significant factor in the Western epidemic of hypertension, as our bodies heighten blood pressure to manage energy use.

Why do some people find it harder to lose weight than others?

This variation relates to the concept of a weight setpoint or weight anchor. Imagine it as an anchor that keeps a ship tethered to one location—similarly, your weight anchor dictates your body’s weight range.

Your weight anchor could be set within the “overweight” or “obese” zone. Even if you work hard at the gym or adhere to a low-calorie diet, your brain’s weight control center may pull you back to your setpoint.

This anchor is influenced by several factors, many of which you can change, but one is immutable: your genetics.

We all know individuals who remain naturally slim and can indulge in their favorite treats without gaining weight. However, about 25% to 33% of the population carries genes that predispose them to weight gain when exposed to Western dietary habits.

This genetic predisposition is heightened through easy access to sugar, refined carbohydrates, processed foods, fructose, vegetable oils, and more. Unfortunately, much of this unhealthy food is readily available in supermarkets, often overshadowing the fresh produce aisles.

This misunderstanding is prevalent among practitioners who advocate for calorie counting; it overlooks the fundamental principle that the type of food we consume acts on our bodies as a form of medicine.

Read more:

So, what should we be eating?

Remember, it’s about lifestyle changes rather than temporary dieting. Dieting implies short-term calorie restriction. However, if you comprehend how different foods impact your body like medications, you will naturally shed pounds. Avoid sugar, refined carbohydrates, and toxic vegetable oils that adversely affect insulin levels.

Opt for homemade meals, and without much struggle, your weight setpoints will begin to decrease. You may find you lose considerably more weight than through conventional exercise efforts. This doesn’t have to be a struggle or cause frustration.

For instance, you could effortlessly replace unhealthy snacks eaten while watching television with a plate of veggies sprinkled with a bit of salt. It is all about recognizing and transforming unhealthy habits into healthier alternatives.

Initially, giving up sugar or chocolate may trigger cravings. However, these can be managed through a technique called “Crave Surfing,” which involves acknowledging the craving without disregarding it. Focus on it, and you will find that these cravings will ebb and flow, becoming less intense over time.

What role should exercise play in weight loss?

If you can dedicate time to the gym for about an hour and a half, engaging in vigorous activities, you could potentially burn 1000 calories daily. Over six days a week, this can significantly impact your weight.

However, for most, this level of control is unattainable unless you are an athlete. Recommendations for 30 minutes of exercise, 3-4 times a week, have minimal effect on weight loss—you may only shed around 2 kilograms annually.

Just like limiting calories, exercise can enhance metabolism efficiency, causing the body to become more adept at conserving energy.

For example, if you engage in a 30-minute workout and burn about 400 calories, it may leave you feeling hungrier. Unless you maintain exceptional willpower, you are likely to consume those 400 calories back. Instead of burning these calories, your metabolism functions to regulate them.

The way to counter this effect involves a combination of calorie restriction and physical activity for optimal results. Our metabolism cannot typically adjust by more than 600 or 700 kilocalories a day. Hence, if you successfully reduce your intake beyond 1000 calories, weight loss is likely to follow—but it is a challenging task that can lead to fatigue and hunger.

This interview has been edited for clarity and brevity.

About our expert, Dr. Andrew Jenkinson

Andrew is a consultant specializing in obesity (weight loss) and general surgical procedures at University College London Hospital.

He is also the author of Why We Eat (Too Much) and How to Eat (and Still Lose Weight).

Read more about nutrition: