Any food or beverage you consume that has calories counts toward your overall calorie intake.
That said, the number of calories you burn each day, known as total daily energy expenditure, is a bit more complicated.
- Basal metabolic rate (BMR): This is the number of calories your body burns when performing basic bodily functions, such as breathing and pumping blood. BMR is also called resting energy expenditure (REE).
- Thermic effect of food (TEF): This refers to the calories used to digest, absorb, and metabolize food.
- Non-resting energy expenditure (NREE): These are calories used during physical activity. NREE is broken down into two categories:
- Exercise activity thermogenesis (EAT) is intentional exercise, such as working out.
- Non-exercise activity thermogenesis (NEAT) is daily movement outside of a formal workout, such as walking and yard work. Many people undervalue how powerful this could be in achieving a calorie deficit.
Several factors affect the rate at which you lose weight. Many of them are out of your control.
Period of weight loss journey
You’re likely to experience more weight loss during the first few weeks of your journey as your body adjusts to being in a calorie deficit and exercising more frequently.
Research suggests this is due to physiological and hormonal changes that occur as your body tries to regain the weight it has lost for survival. This concept is called metabolic adaptation.
Understanding weight loss stages may help you stay on top of your progress.
Sex assigned at birth
Some research suggests that males and females may burn calories at different speeds.
For instance, a 2023 study found that males may have a higher BMR due to more body mass and fat-free mass. This means they burn more calories at rest.
An 8-week study including more than 2,000 participants eating an 810-calorie diet also found that males lost 16% more weight than females, with relative weight loss of 11.8% in males and 10.3% in females.
Age
On average, people gradually gain weight until age 75 years, but after this, body weight may start to decrease.
Older adults tend to experience increases in fat mass and decreases in bone density and muscle mass. Muscle mass weighs more than fat.
Older adults are also more likely to have some health conditions that may cause a loss of muscle mass and function, such as sarcopenia. Similarly, they’re more likely to have multiple health conditions, which could increase BMR.
These factors may all contribute to unintentional weight loss.
Starting weight
Your initial body mass and composition may affect how quickly you can expect to lose weight.
It’s important to understand that different absolute weight losses (in pounds) can correspond to the same relative percentage of weight loss in different individuals.
For example, a 250-lb person who loses 10 lb will lose an equal percentage of their body weight as a 125-lb person who loses 5 lb.
The National Institutes of Health (NIH) Body Weight Planner is a useful guide to help you determine how much you can lose based on your initial weight, age, sex, and how many calories you take in and expend.
Calorie deficit
The extent of your calorie deficit may affect how quickly you lose weight.
For example, consuming 500 fewer calories per day for 8 weeks will likely result in greater weight loss than eating 200 fewer calories per day.
Other factors
Several other factors can also affect your weight loss rate, including:
- genetics
- not getting enough sleep, as this may increase hunger, affect hormones, and cause eating behavior changes
- some medications, such as for depression, hypertension, epilepsy, diabetes, and allergies
- some health conditions, such as chronic stress, depression, hypothyroidism, and Cushing syndrome
- family history of obesity or overweight
There are innumerable weight loss diets available, each promising great results. But it’s important to note that no single diet is the best for weight loss.
A 2020 review of 121 studies examined the weight loss effects of 14 popular diets with different macronutrient ratios. Researchers found that weight loss occurred in all diets, and there were no significant differences long term.
Remember, don’t drastically reduce the number of calories you eat daily. Following a very low calorie diet for long periods is difficult and may contribute to eventually eating more calories and regaining weight.
For the best results, combine a well-balanced diet with regular exercise and high quality sleep.
What are the first signs of weight loss?
Some early signs of weight loss may include your clothes fitting more loosely, feeling less hungry and tired, having more muscle definition, and having a better mood.
How long does it take to lose belly fat?
There’s no single timeline for losing belly fat, as it depends on several factors.
Most studies show that you can’t target a specific body part for fat loss, known as spot reduction. Fat distribution also varies for each person, which means you may have more fat around your abdominal area, while others have more in their arms.
Focusing on maintaining a calorie deficit by eating a well-balanced diet and getting regular exercise could help you lose overall fat, which may contribute to belly fat loss.
Weight loss occurs when you consume fewer calories than you burn.
Many factors affect your weight loss rate, including your sex, age, physical activity levels, starting weight, sleep, and the extent of your calorie deficit.
Remember, weight loss is not a linear process. Some weeks, you may lose more weight, while other weeks, you may lose less or none at all. That’s OK. What matters is keeping things healthy and sustainable.
