Eating too few calories can be the start of a vicious cycle that causes diet distress. When you cut your calories so low that your metabolism slows and you stop losing weight, you probably will become frustrated that your efforts are not paying off. This can lead you to overeat and ultimately gain weight.
It simply takes time. Another common reason why people report not losing weight despite reducing their calories is that they don't give it enough time. Our bodies will do their utmost to hold on to our fat reserves and you often have to be in a calorie deficit for a while before you will see any meaningful weight loss.
Undereating may cause weight gain for some people, but even if it doesn't, it's important not to eat so little that it adversely affects your health. From constipation to immune dysfunction, not eating enough can lead to a host of health issues.
If you take in fewer calories than needed, you will lose weight ( 1 ). Restricting intake to fewer than 1,000 calories daily can slow down your metabolic rate and lead to fatigue since you're not taking in enough calories to support the basic functions that keep you alive.
Regularly eating fewer calories than your body requires can cause fatigue and make it more challenging for you to meet your daily nutrient needs. For instance, calorie-restricted diets may not provide sufficient amounts of iron, folate or vitamin B12. This can lead to anemia and extreme fatigue (16, 17, 18).
For most people, there are no serious dangers involved in eating one meal a day, other than the discomforts of feeling hungry. That said, there are some risks for people with cardiovascular disease or diabetes. Eating one meal a day can increase your blood pressure and cholesterol.
It can help with weight loss
Fasting one or two days a week may be a way for you to consume fewer calories over time. You may find this easier to do than cutting back a certain number of calories every day. The energy restriction from a 24-hour fast may also benefit your metabolism, helping in weight loss.
Fasting for a certain number of hours each day or eating just one meal a couple days a week, can help your body burn fat. And scientific evidence points to some health benefits, as well.
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.
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.
To reverse diet without gaining weight, slowly increase your calorie intake to a higher target calorie goal. By doing this in a strategic, slow manner, you may be able to boost your metabolism, manage your hunger levels, and prevent or reduce rapid weight regain.
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.
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.
Weight gain and fluctuations in weight can happen for a variety of reasons. Many people progressively gain weight as they age or make changes to their lifestyle. However, fast weight gain can be a sign of an underlying health condition, such as a problem with the thyroid, kidneys, or heart.
Still, to ensure healthy weight loss and adequate nutrient intake, women should not consume fewer than 1,200 calories per day, and men no fewer than 1,500 calories ( 5 ).
Remember: eating too little is just as unhealthy as eating too much. Find the right amount of food that works best for you, and don't be afraid to experiment with eating more if your health and performance aren't where you want them to be!
Skipping breakfast and other meals is one behavior studied as a factor influencing weight outcomes and dietary quality. Based on evidence that skipping breakfast reduces total daily caloric intake, some weight-loss recommendations include skipping breakfast (i.e., intermediate fasting) as one strategy to use.
But on average, you should lose 10 pounds in exactly 5-6 weeks for a healthier and more achievable estimate. This means that you lose around 2 pounds per week, which is in line with the CDC's recommendation for safe weight loss at a rate of 1–2 pounds per week, a sustainable goal.
"This means to lose 1 pound, you'll need to walk roughly 35 miles or 70,000 steps. Over the course of a week, this means targeting 10,000 steps a day," says Davis. At this rate, you could lose 10 pounds in 10 weeks.