A calorie deficit occurs when you consistently provide your body with fewer calories than it needs to support calorie expenditure. A good rule for healthy weight loss is a deficit of about 500 calories per day; this should produce a loss of 1 pound per week. So, a low-calorie diet can have 1, 200 to 1, 500 calories a day for women and 1, 500 to 1, 900 calories a day for men.
A calorie deficit means that the number of calories you burn exceeds the number of calories you eat, which results in weight loss.
There are three possible ways to achieve a calorie deficit. The first is to increase the number of calories you burn through exercise.
1 The second is to reduce your calorie intake through diet. The third is to do a little of both.
2Achieving a calorie deficit can be beneficial for weight loss and overall health, but creating a calorie deficit that’s too large can lead to health risks.
3 It's important to talk to a healthcare provider before starting a calorie deficit in order to lose weight safely and effectively.
The safest way to achieve a calorie deficit is to make changes that allow you to burn more calories than you eat while still properly nourishing your body.
You can reach a calorie deficit by reducing your calorie intake or increasing your calorie output through physical activity. You can also do both together.3 For example, you’ll create a 500-calorie deficit by cutting 250 calories from your diet per day and burning an additional 250 calories through exercise.
You can also cut calories through intermittent fasting, which involves avoiding eating for a certain period of time. There are four methods for intermittent fasting:4
To determine how to achieve a calorie deficit, you first need to choose an approach. If you’d like to reduce your calorie consumption through intermittent fasting, choose one of the four methods listed above.
If you plan to achieve a deficit by increasing your calorie output through exercise, you'll need to track the amount of calories you burn.
Based on your weight and activity type and length, you can estimate how many calories you'll burn in a workout. For example, a 154-pound person will burn 280 calories walking at 3.5 miles per hour for one hour.1
You can also use a wearable tracker device to measure your activity and personal calorie output throughout the day.5
If you are creating a deficit by reducing the number
of calories you consume, it may be helpful to track your meals, snacks, and beverages using a nutrition app. Seeing where your calories come from can help you decide how and when to cut back.6
For example, you can lower your daily calorie intake by:
Keep in mind that once you achieve a calorie deficit, it can be difficult to predict the amount and rate of weight loss you’ll experience. Each person's metabolism and activity level is different, both of which can play a role in calorie outputs.11
When done safely, achieving a calorie deficit has many potential benefits. A calorie deficit accomplished through an increase in physical activity may result in reductions in:1
Successful calorie deficits may also result in weight loss. A two-year study of over 200 people found those who consumed 12% fewer calories per day than their typical diets lost 10% of their body weight.12
In the same study, those who achieved a calorie deficit also had reductions in blood pressure and cholesterol as well as inflammatory factors and thyroid hormones. There is some evidence that the latter two outcomes are tied to longer lifespan and reduced age-related disease risk.12
Other research has shown calorie restrictors experience improvements in quality of life, mood, and sleep compared to those who did not change their calorie consumption.3
Another study concluded that in humans, calorie restriction remains the best way to prevent and treat obesity and its complications. Researchers noted that moderate calorie restriction can offer health benefits even in people who do not have obesity. This was true whether the calorie restriction was achieved through intermittent fasting or restricted eating combined with regular exercise.3