Lifestyle-Related Weight Gain

Getting less than seven hours of sleep per night is commonly associated with weight gain across a range of studies. Insufficient quality sleep increases ghrelin (the hormone that signals hunger) while decreasing leptin (the hormone that signals fullness).   

Chronic short sleep has been linked to raised hunger hormone levels and disrupts metabolism. A systematic review published in SLEEP found that sleep loss was associated with increased caloric intake. Sleep-deprived individuals eat an extra 385 kilocalories per day in some trials, roughly equivalent to an additional small meal. The effects on appetite appear to be particularly pronounced in the late afternoon and evening, times when snacking is most likely to contribute to fat storage.

Shift work and irregular sleep schedules heighten these effects by disrupting the body’s circadian rhythm, further impairing appetite regulation and metabolic function. 

Aim for seven to nine hours per night: Prioritising sleep can help regulate appetite hormones and reduce cravings, supporting healthier eating habits without requiring significant conscious effort.

Stress has a direct physiological effect on body weight through the stress hormone cortisol. When stress becomes chronic, cortisol levels remain persistently elevated. 

Research shows that chronically elevated cortisol stimulates appetite, including cravings for high-calorie, sugary, and fatty comfort foods. It also promotes fat storage in the abdominal area (belly) by enhancing lipoprotein lipase activity in adipose tissue. 

Cortisol also contributes to insulin resistance over time, making it more difficult for the body to regulate blood sugar and increasing the likelihood of excess energy being stored as fat.

One study found that stressed women burned 104 fewer calories per day than non-stressed controls. That difference could translate into around 5 kg of weight gain over a year.

Beyond direct metabolic effects, chronic stress can lead to:

• Compulsive or emotional eating 

• Reduced motivation for an active lifestyle 

• Worsening of other issues like mental health conditions 

• Disrupted sleep

Stress-management techniques and consistent daily routines can help lower cortisol levels and reduce stress-related eating behaviours.

Sitting for long periods reduces the number of calories your body burns each day. Whether at a desk, in the car, or in front of a screen, this can contribute to gradual weight gain over time.

Both the UK Chief Medical Officers and the World Health Organisation recommend that adults do:

• At least 150 minutes of moderate-intensity activity per week, such as walking, swimming or cycling 

• Muscle-strengthening exercise at least two days per week 

Strength training can be especially useful for maintaining muscle mass, which helps keep your metabolism working efficiently as you age.

It doesn’t have to mean joining a gym and starting a heavy physical routine. Small, consistent changes like taking the stairs, walking during a lunch break, or simply standing up regularly throughout the day all add up and can make a real difference over time.

What, how much, and when we eat can all influence body weight. Regularly consuming more calories than the body burns and uses can lead to weight gain over time.

Some dietary habits that may contribute to weight gain include:

• Frequent consumption of ultra-processed foods and sugar-sweetened drinks.

• Large portion sizes.

• Regular takeaways and convenience foods.

• Eating while distracted, such as in front of a television or computer.

• Late-night eating and irregular meal patterns.

Ultra-processed foods are often high in calories and lower in fibre, which can make it harder to feel full after eating. This may lead to increased calorie intake throughout the day.

Simple strategies can help support healthy eating habits and long-term weight management, such as:

• Planning meals ahead 

• Eating mindfully 

• Choosing more fibre-rich foods, vegetables, lean protein, and whole foods.

Staying hydrated is also important. Thirst can sometimes be mistaken for hunger, which may lead to unnecessary snacking or calorie consumption.

The cycle of repeated weight loss and regain, or yo-yo dieting, may also contribute to long-term weight gain by disrupting metabolic set points. This cycle may also make subsequent weight management progressively harder. 

Alcoholic drinks contribute additional calories that are frequently overlooked in dietary intake assessments. Beyond their caloric content, alcoholic beverages can:

• Increase appetite

• Lower inhibitions around food choices

• Disrupt sleep quality

• Dehydrate you

• Causes high blood pressure 

• Impair the body’s ability to burn fat efficiently by affecting liver metabolism.