Our bodies need energy to function. This energy comes from food which is converted into calories. When we keep eating more calories than our bodies need to function, the excess calories deposit as fat, as stores for future energy needs. We call this calorie surplus.
However, for losing weight, we need to think in the reverse. We have to make our bodies use these fat stores as energy and that’s where a calorie deficit diet comes into play.
What is Calorie Deficit?
So what does calorie deficit means? Calorie deficit is the difference between calories we use every day and the calories we give to our bodies by eating.
As we noted above, a successful weight loss can only happen when we make our bodies burn fat deposits. The next question will be how much of a calorie deficit should you have.
One pound of fat roughly equals 3500 calories. Therefore, in order to lose one pound of fat, you have to burn 3500 calories, given that you are maintaining the same calorie intake as before. So we can say that you need to have a calorie deficit of 3500 to lose one pound.
This can be achieved by two ways. Either you burn these calories by getting physically active or you reduce your calorie intake by about 500 every day to lose one pound in a week.
So how much exercise it will take to lose one pound? Well, if you solely rely on walking as exercise, it takes one mile brisk walk to burn 100 calories. (1) Going by that speed, you will need to walk 35 miles. This is a long shot. So we need to think of the other way of creating calorie deficit and that is by eating less and eating healthy.
How Many Calories Do I Need?
But first we need to understand your current calorie intake per day and the minimum recommended daily calories. According to US Dietary Guidelines, the minimum recommended calories for a female are 1600 whereas it is 2000. (2)
Another good way to measure your calories need per day is to use a tdee calculator which will measure the total daily energy expenditure based on your lifestyle, height, weight and gender. This will also give you your BMR.
What is BMR? This is the basal metabolic rate, which is the minimum calories your body needs to function without any physical activity. This should be your target for the minimum calories at least. For calculating your BMR, you can use this calculator.
But it doesn’t mean that you should eat these much calories every day. You can create a calorie deficit and burn fats stores to make up for the difference in calorie intake and expenditure.
Does Calorie Deficit Diet Work?
In fact, this is the only healthy way to lose weight. There is no other way to lose weight. But your calorie deficit should be in a healthy range and you should stay away from extreme diets. Ideally you should target between 10% to 15% reduction in your calories.
A recent study has shown that calorie restricted diet over a two year period led to 7.5kg of weight loss. No only that but it also improved cardiovascular risk factors. (3)
It has also been shown that the weight loss on a calorie deficit diet persists even after two years which means that calorie restriction leads to long term weight loss. (4)
Another study published in The Journal of Gerontology found that calorie restricted diet is feasible for long term and that subjects lost up to 11.7 kg weight loss over a period of two years. (5)
How to Follow a Calorie Deficit Diet?
The key is to restrict calorie intake. But it doesn’t mean starving. You can achieve this still by eating full. Here is how to do this:
- Focus on eating low calorie foods. These foods will make you full for longer, take more time to digest and reduce your overall calorie intake without feeling hungry. This will mean decreasing any junk food consumption, eating low carb diet, focusing on more healthy protein, avoiding high fat foods, and including more vegetables and fruits in your diet.
- Eat more negative calorie foods. Yes, these foods do exist. They are the types of foods that will burn even more calories to digest these than they will provide to your body. This essentially means calorie deficit without hunger cravings. Some of such foods include berries, cucumbers, carrots, celery, apples, zucchini, grapefruit, lettuce and broccoli.
Why Exercise is Important?
Exercise is a vital element of any weight loss program. It not only helps improve your overall health, it is key to a sustained weight loss.
When you exercise, you burn calories during the process. But the real benefit happens after the exercise as well.
It has been shown that our bodies continue to burn more calories in resting state (called basal metabolic rate) up to 48 hours after exercise. (6)
Exercise has been shown to prevent weight regain after you have lost it. So it important when you want to lose weight and keep it off. (7)
Anybody serious in losing weight by calorie deficit should include about 300 minutes of moderate intensity exercise in their weekly schedule.
And don’t forget to include resistance training/weight training for at least two days a week to build and maintain muscle mass. Increased muscle mass means increased resting BMR and more resting energy expenditure.
Why You are Not Losing Weight on a Calorie Deficit Diet?
While it can be a guaranteed way to lose weight safely, there might be occasions where you may not lose weight as per your desire. However, it can be due to several reasons:
- Your body may be building muscle. Which is good because you might not be losing weight on scale but body will surely be losing fat.
- Your are trying to create your all calorie deficit by spending hours at a they gym without modifying your diet. Unless you also take care of your diet, you will take ages to lose weight simply by exercise.
- Certain health conditions also work against your weight loss efforts. Some of the reasons might include thyroid disorders, birth control pills, antidepressants, polycystic ovarian syndrome and menopause. In that case get yourself checked from a doctor.
- You are stressed. Stress increases production of cortisol hormone which induces water retention and hence increased water weight.
- You might be comparing your progress with others. Not two individuals lose weight in the same pattern. But if you persist, you will surely lose weight on a low calorie diet.
- Are you being patient? Because you have to wait to see the results. Maybe you are drawing conclusions before time before going through the whole diet plan. At least give it a few weeks and you will see results.
Is it Safe?
As long as you are not following an extremely low calorie diet plan and not drastically cutting any of the macronutrients, it is a safe diet and guaranteed to lose weight.
The Bottom Line
Calorie deficit definitely works for long term weight loss. All you need to do is to start eating responsibly and fit in some exercise in your weekly schedule.