For weight maintenance, the Dietary Guidelines for Americans 2020–2025 suggest a range of 1,600–2,400 calories for women and 2,200–3,000 for men — so you could consider anything below these numbers a low-calorie diet.
Calories and Your Health
But if your calorie intake dips too low, says Lummus, your body could go into starvation mode. "Your body will start to store fat because it thinks it is not going to get anything," says Lummus. "You will be at a point where your body is kind of at a standstill."
However, calorie intake should not fall below 1,200 a day in women or 1,500 a day in men, except under the supervision of a health professional. Eating too few calories can endanger your health by depriving you of needed nutrients.
A 1,200-calorie diet is much too low for most people and can result in negative side effects like dizziness, extreme hunger, nausea, micronutrient deficiencies, fatigue, headaches, and gallstones ( 23 ). Furthermore, a 1,200-calorie diet can set you up for failure if long-term weight loss is your goal.
1,500 calories per day would be considered a low caloric intake for most people and would generally not be recommended for the long term.
Eating too few calories can cause a major decrease in metabolism. Although a calorie deficit is needed for weight loss, it can be counterproductive for your calorie intake to drop too low.
As a general rule, people need a minimum of 1,200 calories daily to stay healthy. People who have a strenuous fitness routine or perform many daily activities need more calories. If you have reduced your calorie intake below 1,200 calories a day, you could be hurting your body in addition to your weight-loss plans.
If you drastically slash calories and are eating a very low-calorie diet (Think: less than 1,000 calories for women and less than 1,200 calories for men), “starvation mode” can actually be starvation. Starvation from chronic undereating can be counterproductive to weight loss and dangerous to your health.
Very low-calorie diets (around 800 calories per day), cause rapid weight loss and increase the risk of gallstones, which may cause abdominal pain and require surgery.
BOTTOM LINE: A balanced 1,500-calorie diet rich in nutritious foods fits the needs of many people who want to lose fat and improve health. Still, while 1,500 calories may be a good guideline for many people, it may not be enough for some.
Bare Number of Calories
The National Institute of Diabetes and Digestive and Kidney Diseases says that when eating real food, women may be able to meet their needs eating as few as 1,000 to 1,200 calories a day, and men can do the same on 1,200 to 1,600 calories a day.
Very low calorie diets should only be followed under medical supervision for a maximum of 12 weeks. Do not follow a very low calorie diet unless a GP has suggested it to you.
It is commonly said that if you eat too few calories, your metabolism will slow down to a point where you no longer lose weight. Part of this is true: as you lose weight your energy expenditure does drop. However, consuming too few calories cannot and will not cause you to gain weight. This is simply impossible.
Typical signs that you're not eating enough can include losing weight, feeling tired, getting ill more often, hair loss, or skin problems. In time, menstrual irregularities and depression may occur. Children may not grow as expected.
Unintentional weight gain occurs when you put on weight without increasing your consumption of food or liquid and without decreasing your activity. This occurs when you're not trying to gain weight. It's often due to fluid retention, abnormal growths, constipation, or pregnancy.
People may turn to 1,000 calorie diets when they are desperate to lose weight quickly, such as before a vacation. While adults could follow this type of diet relatively safely for a couple of weeks, it is not something that doctors advise for extended periods.
If you don't eat enough, your metabolism switches to slow-mo. Severe diets, especially when you also exercise, teach your body to make do with fewer calories. That can backfire, because your body clings to those calories, which makes it harder to take weight off.
Generally, the recommended daily calorie intake is 2,000 calories a day for women and 2,500 for men.
In humans. Ordinarily, the body responds to reduced energy intake by burning fat reserves and consuming muscle and other tissues. Specifically, the body burns fat after first exhausting the contents of the digestive tract along with glycogen reserves stored in liver cells and after significant protein loss.
After 7 Days
By one week, however, the bodies of most starving people will be actively breaking down muscle in order to obtain protein.
Short-term risks of eating 1,000 calories a day may include dizziness, hunger, gallstones, nausea, fatigue, headaches, and nutrient deficiencies. It can lead to nutrient deficiencies, slow metabolism, and make bones weaker if you exercise along with a low-calorie diet.
You can't lose weight on 1200 calories a day because you're no longer in a calorie deficit. Your body has adapted to what it's been doing and plateaued. If you start your diet with a 500 calorie deficit per day, your body adapts to this in various way so that over time your energy requirements are reduced.
You're holding onto water weight.
It's as simple as that really, unless you're incredibly small and in active you should and will lose weight on 1000 calories unless of course you're chronically stressed or really suck at counting calories.
The speed that your body burns energy for its everyday functions is called your metabolic rate. For most people, this doesn't start to slow down until around the age of 60, but it does change if your weight changes.