There are many reason why losing weight to quickly is risky. A healthy weight-loss rate is generally considered to be 1 to 2 lbs. per week, which helps you achieve a reasonable weight loss that you are more likely to keep off. Below are possible risks of dropping weight too rapidly. Please understand that this does not happen to everyone. Being that our bodies are all made differently, we react differently to everything. These, however all have the potential to happen to anyone in a rapid weight loss situation.
MALNUTRITION
Now I’m sure a lot of people see this word and instantly think of someone underweight. It just so happens that an overweight person can suffer from malnutrition just as easily. Your body relies on a combination of vitamins and minerals to maintain daily functions. If you restrict your calories too low, you may be missing out on vital nutrients required to maintain your body’s health. You may begin to notice the effects of this if you experience hair loss, muscle weakness/cramping/spasms or unexplained fatigue.
GALLSTONES
Your body requires fat for energy and normal body functioning. If you cut fats entirely from your diet or overly restrict your calories, your body begins to use stored fats. To metabolize these fats, your gallbladder may secrete extra bile. This is dangerous because added bile increases your risk of gallstones. Painful collections of bile and cholesterol can affect your bladder’s ability to empty. Rapid weight loss may also cause silent gallstones (painless gallstones) to become symptomatic. Studies have shown that people who lose more than 3 pounds per week may have a greater risk of developing gallstones than those who lose weight at slower rates. Studies have shown that 10 to 25 percent of people on a low calorie diet developed gallstones. Following a diet too low in fat or going for long periods without eating (skipping meals, flushing, or fasting), a common practice among dieters, may also decrease gallbladder contractions. If the gallbladder does not contract often enough to empty out the bile, gallstones may form. Aside from bloating, nausea and vomiting, gallstones can also cause severe pain in the upper abdomen, between the shoulder blades and in the lower back. Surgery may be necessary to remove large stones or even the gallbladder itself.
HEART RHYTHM DISORDERS
Your body relies on sodium, potassium and a number of other minerals to maintain heart function. If you lose weight too quickly via dramatic calorie restriction , fasting, or flushes, your body may not be able to maintain a normal heart rhythm. You may experience a heartbeat that feels off pace, slows or beats too fast. This can wear out your heart muscle or even cause cardiac arrest because your heart may not be able to pump enough blood to your extremities
EXCESSIVE KETONES
Restricting your carbohydrate intake below 130 g of carbohydrates per day to experience weight loss can have harmful effects. Ketones (fats that have not completely broken down), can build up in your blood. The result of this is increased uric acid production. Uric acid contributes to joint swelling known as gout, taxes your kidneys and can cause kidney stones to develop.
METABOLIC PROBLEMS
Your body fat levels are directly proportional to a signaling hormone called leptin. Leptin levels are monitored by the hypothalamus section of your brain. Leptin controls appetite, modulates your metabolism and promotes fat burning. If fat levels drop very quickly, there is a subsequent rapid drop in leptin levels. A rapid drop in leptin levels will trigger the starvation response. The starvation response causes a reduction in your daily energy expenditure by lowering your metabolism, increasing hunger and also prompting the breakdown of muscle for energy. In addition, the starvation response works to ensure you regain not only the fat you have lost, but also some extra fat to protect you from similar bouts of food restriction.
PSYCHOLOGICAL COMPLICATIONS
Very low-calorie diets may result in a rapid initial weight loss but many dieters find that the severe hunger associated with eating so little food makes it hard to stick with this type of eating program for long periods of time. Hunger levels may become so severe that the dieter falls into a diet/binge cycle of eating. Crash dieting may lead to eating disorders like anorexia and bulimia. A very-low-calorie diet can also be socially exclusive, especially if friends and family are eating normally. Depression and anxiety can set in because the mental weight loss process takes time to register. With things changing at such a quick pace some find themselves overwhelmed.
WEAKENED IMMUNE SYSTEM
Research shows that more than 90 minutes of high-intensity endurance exercise can make athletes susceptible to illness for up to 72 hours after the exercise session. This is important information for those who compete in longer events such as marathons or triathlons. Intense exercise seems to cause a temporary decrease in immune system function. During intense physical exertion, the body produces certain hormones that temporarily lower immunity. Cortisol and adrenaline, known as the stress hormones, raise blood pressure and cholesterol levels and suppress the immune system.
LOSS OF MUSCLE
When the body does not get enough nutrients from the diet (common in very low calorie or liquid diets, which are used for rapid weight loss), it resorts to eating away at the muscles for energy. Fat is not a very effective source of energy and the body considers fat as energy reserve, thus only using it as a last resource. Loss of muscle leads to a sluggish metabolism, which in turn will make it easier to regain weight once the person goes back to eating normally.
DEHYDRATION
People who are losing large amounts of weight usually restrain their water intake as well to prevent bloating. Dehydration can lead to a number of problems, including dizziness, lack of energy, kidney stones, diarrhea and vomiting. Excessive dehydration can lead to kidney failure, heart attack or a heat stroke.
HAIR LOSS
Hair loss is common in diet programs that cause rapid weight loss for long periods of time, such as the case of liquid diets or very-low calorie diets (under 800 calories per day). Hair needs protein to grow and maintain its health. In diets that cause rapid weight loss, protein is usually reduced to a small percentage of the daily diet, as dieters usually need to concentrate in either liquids or produce to lose weight. The lack of protein in the diet will lead to brittle hair and eventually hair loss, as the body will use whatever little protein is consumed for other, more vital organ functions.
These are just a few example of what can happen with rapid weight loss. Please don’t ever think that just because it didn’t happen to someone else, that it means it can’t possibly happen to you.

5 Comments
Good article, Pamela. All of which we have heard before.
But there is a lot of contradictory information out there, also. Most recently I have been watching “Fat, Sick, and Nearly Dead” (streams free on Hulu) where a couple of guys go on a 60 day juice fast (mostly greens), and their blood profiles are monitored every 10 days. And they lose an incredible amount of weight, AND get healthier.
The companion book of the same name has a forward by Dr. Joel Fuhrman and and afterword by Dr. Dean Ornish, who seem to approve. And they are both respected medical professionals.
All of which makes choosing a diet confusing.
Thank you for your comment jpwav716. Unfortunately the above listed side effects are not as well known as you may think. I agree that there are many different opinions on rapid weight loss however this article is to forewarn about POTENTIAL risk. As I stated these do not happen to everyone and in all fairness sometimes it can take a while before any of these set in. Here’s my opinion. To be successful don’t choose a diet, you choose a lifestyle. If what you are doing to lose weight is not going to be a permanent change in your every day life, it runs a very high risk of not only making the weight lost return, but make your weight gain even higher. I personally promote healthy lifestyle changes, not diets.
Good response, Pamela.
Interesting concerns. Is it not possible to loose the weight quickly, but then ease into a very healthy lifestyle once the weight is lost? Thus, suffering for a brief weight loss period but then taking extra care and recovering afterwards.
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