Weight Loss by Eating Less Than 1000 Calories a Day

If you’re thinking of losing weight by eating less than 1000 calories a day, you’ve come to the right place.

In this article, I’ll cover some key questions, like: will you lose weight by doing this? And if so, how much? Plus, I’ll talk about whether or not it’s safe to eat so little.

Table of Contents

1. Will You Lose Weight by Eating Less Than 1000 Calories a Day?
2. How Much Weight Will You Lose by Eating Less Than 1000 Calories a Day?
3. Is It Safe to Eat Less Than 1000 Calories a Day?
4. Closing Remarks

Will You Lose Weight by Eating Less Than 1000 Calories a Day?

Let’s start with the basic principle of weight loss: you will lose weight if you eat fewer calories than you burn or if you burn more calories than you eat.

Your body burns calories every day, even when you’re not exercising. It burns calories for your daily activities and basic bodily functions, such as respiration, digestion, blood circulation, cell regeneration, etc.

The total number of calories you burn every day is called your Total Daily Energy Expenditure (TDEE). The number of calories you burn for basic bodily functions is called the Basal Metabolic Rate (BMR). Your BMR is the largest part of your TDEE.

Your TDEE depends on your age, gender, height, weight, and level of physical activity. But, the Dietary Guidelines for Americans 2020-2025 estimates the calorie needs of adult range from 1,600 to 2,400 calories per day for women and 2,000 to 3,000 calories per day for men.

The British NHS also estimates similar numbers. According to them, the average men need about 2,500 calories per day to maintain a healthy body, while the average women need about 2,000 calories per day.

So, unless your TDEE is below 1000 calories per day, which is highly unlikely, you’ll almost certainly lose weight if you’re eating less than 1000 calories a day. The question is, is it healthy? Can the resulting weight loss last for a long time?

How Much Weight Will You Lose by Eating Less Than 1000 Calories a Day?

It depends on how many calories you eat in a day and how much your TDEE is. Say, you are an adult woman with a TDEE of 2,000, and you want to lose weight by eating 800 calories a day. Thus, the calories you lose in a day are 2,000 – 800 = 1,200 calories.

In 3 days, the calories you lose are 3,600 calories. Since 1 pound of fat is equal to 3,500 calories, you have lost more than 1 pound of fat in 3 days. In a month, you’ll lose more than 10 pounds of fat.

Now, how much weight will you lose if you eat 700 calories a day? Well, the calories you’ll lose in a day are 2,000 – 700 = 1,300 calories. In a month, you’ll lose around 39,000 calories, which equals about 11 pounds of fat.

Say, you want to be more extreme and eat only 600 calories per day, then you’ll lose 2,000 – 600 = 1,400 calories a day. In a month, you will lose about 42,000 calories, which equals 12 pounds of fat.

All of these examples assume almost all of the calories you lose come from fat, which is highly unlikely. When you go on an extreme diet, especially if you don’t strength train, you’re also more likely to lose lean body mass. However, the figures can be used as a rough estimate.

Now, losing 10-12 pounds in a month, that’s pretty fast, right? But again the question is, is it healthy? Can the lost weight be kept off for a long time? In the next section, I’ll discuss these issues. And if you want to know how to calculate your TDEE, read my article here.

Is It Safe to Eat Less Than 1000 Calories a Day?

A safe calorie deficit for most people is around 15-30 percent below their TDEE. So, unless your TDEE is below 1400 calories, which is unlikely, eating less than 1000 calories a day is considered unsafe.

Your body needs a certain amount of calories to function properly. Consuming too few calories can lead to a variety of negative health consequences.

Firstly, your metabolism is likely to be damaged. When you cut a lot of calories, your body enters starvation mode, slowing down your metabolism to save energy.

This metabolic adaptation means that your body is able to function on fewer calories than it used to, making it harder to lose weight. As a result, your weight loss progress will slow down.

Additionally, your body will start to break down muscle tissue for energy. This can further slow down your metabolism and make it harder to lose weight in the long run.

This metabolic slowdown can cause faster weight regain when you stop the diet. And it’s very hard to stick to a very low-calorie diet for a long time. So, you’ll probably end up quitting the diet.

Furthermore, consuming too few calories can cause fatigue, weakness, and dizziness. This can hinder your ability to perform daily tasks and exercise.

It can also cause malnourishment and compromise your immune system. Your body needs a balance of nutrients to function correctly, and severely restricting calorie intake can lead to deficiencies in essential vitamins, minerals, and protein.

Lastly, rapid weight loss through severe calorie restriction increases the risk of developing gallstones. When you lose weight too quickly, your liver secretes more cholesterol into the bile, which can form gallstones.

Also, a very low-calorie diet may cause inadequate emptying of the gallbladder. This can cause the bile to become stagnant and concentrated, increasing the risk of gallstone formation.

Closing Remarks

As we can see, you can lose 10-12 pounds in a month if you eat less than 1000 calories per day. And that’s a pretty fast weight loss.

However, eating less than 1000 calories a day can harm your body. It can damage your metabolism; cause muscle loss, fatigue, weakness, dizziness, and malnourishment; compromise your immune system; and increase the risk of gallstone formation.

Also, you most likely won’t stick to the diet for long. And when you stop the diet, you can quickly regain your weight because your metabolism has been damaged.

So, eating less than 1000 calories a day is unsafe and unsustainable for most people. Instead, a healthy and sustainable weight loss strategy involves a modest calorie reduction, balanced diet, and regular exercise.