But many health care providers agree that a medical evaluation is called for if you lose more than 5% of your weight in 6 to 12 months, especially if you're an older adult. For example, a 5% weight loss in someone who is 160 pounds (72 kilograms) is 8 pounds (3.6 kilograms).
According to many experts, losing 1–2 pounds (0.45–0.9 kg) per week is a healthy and safe rate (1, 2, 3 ). Losing more than that is considered too fast and could put you at risk of many health problems, including muscle loss, gallstones, nutritional deficiencies and a drop in metabolism ( 4 , 6 , 7 , 8 ).
If you're losing weight without trying and you're concerned about it, consult your health care provider. As a rule of thumb, losing more than 5% of your weight over 6 to 12 months may indicate a problem.
Losing weight too quickly can damage your metabolism
If you lose more than about 8 pounds in a month, not only will you likely not be able to keep it off, but it also means you probably engaged in unhealthy behaviors to get there.
So what is the magic number to lose weight and keep it off? According to the Centers for Disease Control and Prevention (CDC) , it's 1 to 2 pounds per week. That means, on average, that aiming for 4 to 8 pounds of weight loss per month is a healthy goal.
Even a modest weight loss of 5% to 10% of your total body weight is likely to produce health benefits, such as improvements in blood pressure, blood cholesterol, and blood sugars. For example, if you weigh 200 pounds, a 5% weight loss is 10 pounds, bringing your weight down to 190 pounds.
But many health care providers agree that a medical evaluation is called for if you lose more than 5% of your weight in 6 to 12 months, especially if you're an older adult. For example, a 5% weight loss in someone who is 160 pounds (72 kilograms) is 8 pounds (3.6 kilograms).
According to the American Cancer Society, significant weight loss happens most often with cancers that affect the stomach, pancreas, esophagus and lung.
Causes of unintentional weight loss
It can also be caused by malnutrition, a health condition or a combination of things. Some causes of unintentional weight loss include: mental health conditions, such as depression, anxiety, eating disorders and obsessive compulsive disorder (OCD)
Rapid weight loss usually occurs from extreme calorie deprivation, for example, people who go from eating 3,000 to 1,200 calories a day, says Gans. Trouble is, our body recognizes this as a sign of limited food supply and goes into starvation mode.
Rapid and drastic weight loss can lead to various complications. It includes mainly muscle loss, metabolic changes and nutrient deficiencies. In addition, dehydration, electrolyte imbalance, fatigue gallstone formation are other side effects.
Losing more than 1 or 2 pounds (0.5 to 1 kg) a week is not safe for most people. It can cause you to lose muscle, water, and bone density. Rapid weight loss can also cause some side effects including: Gallstones.
When should I see a doctor about unexplained weight loss? You should consult your physician if you have lost more than 5 percent of body weight or 10 pounds without trying in a period of 6 to 12 months. This is especially important if you have other symptoms, too.
Unexplained weight loss is a decrease in body weight, when you did not try to lose the weight on your own. Many people gain and lose weight. Unintentional weight loss is loss of 10 pounds (4.5 kilograms) or 5% of your normal body weight over 6 to 12 months or less without knowing the reason.
Although there are more than 200 different cancer types and various potential warning signs for each – there is one symptom that is shared by many different types. Sudden and unexplained weight loss may be a warning sign of cancer, and is often one of the very first signs of the disease.
Stress and weight loss
What's more, the stress hormones that our bodies release can speed up our metabolism, causing us to burn calories faster. In more extreme cases, prolonged stress may lead to depression, which can also cause weight loss.
On average, it's not uncommon to lose 10 to 15 percent of your overall body weight due to anxiety and the chronic stress it causes. Always talk with your doctor if you've lost a lot of weight in a hurry.
An aggressive calorie deficit is anything more than 30% of your current maintenance calories.
"Women and men of average height need to gain or lose about three and a half and four kilograms, or about eight and nine pounds, respectively, for anyone to see it in their face.
When significant weight loss occurs, it's then hard for the collagen and elastin fibers to return to their original, pre-weight-gain state². This is mainly observed when rapid weight loss occurs, as the fibers shrink and contract too quickly. This is what leads to loose or excess skin during significant weight loss.
As per experts, losing around 0.5 kilos of weight in a week is ideal, which makes it two kilos in a month. To do so, consume a calorie deficit diet along with regular exercise and healthy eating. Losing around 1.5 to 2.5 kilos of body weight in a month is considered healthy.
But do you really know what's realistic? Over the long term, it's smart to aim for losing 1 to 2 pounds (0.5 to 1 kilogram) a week. Generally to lose 1 to 2 pounds a week, you need to burn 500 to 1,000 calories more than you consume each day, through a lower calorie diet and regular physical activity.
“There's no reason to weigh yourself more than once a week. With daily water fluctuations, body weight can change drastically on a day-to-day basis,” says Rachel Fine, registered dietitian and owner of To the Pointe Nutrition. “Weighing yourself at the same time on a weekly basis will give you a more accurate picture.”