Most of us don’t like the concept of changing our daily routine. If we have to lose weight, we prefer to do it as quickly as possible.

In fact, losing several pounds a week actually motivates us to keep going. But can rapid weight loss be harmful?

There are both pros and cons to quickly losing weight, Dr. Kathryn Boling, a family medicine physician at Mercy Medical Center in Baltimore, Maryland, told LifeZette.

“A recent study in the Lancet revealed that obese people on very low-calorie diets were more likely to reach their weight loss goal, and less likely to drop out of the study. Also, since their food choices were so limited, they found the diet easier to follow.”

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But hang on. Boling says this type of regimen puts dieters at risk for a variety of health problems, including constipation, an increased risk of gallstones, sagging skin, possible triggering a gout attack, fatigue, lowered metabolism, and possible electrolyte disturbance.

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Those aren’t even the worst health hazards, however. Boling said there have been at least three documented cases in which these extreme measures resulted in death.

“Rapid weight loss can produce serious conditions such as dehydration and malnutrition,” said one expert.

“All of the cases involved wrestlers who were attempting to have very rapid weight loss combining decreased calories, decreased hydration and the wearing of suits to increase body temperature — each wrestler died of hyperthermia and dehydration.” 

While death is extremely rare, Liz Josefsberg, a New York-based health and wellness expert, said, “Rapid weight loss can produce serious conditions such as dehydration and malnutrition, along with less dangerous side effects like headaches, dizziness, irritability, and even hair loss.”

But some rapid weight loss may be inevitable. Brad Davidson, a fitness expert and nutritionist, and the author of “The Stark Naked 21-Day Metabolic Reset,” said that in the early stages of weight loss, “It is not uncommon for people to lose 8 to 15 pounds over the first four weeks.”

However, he explained, “This is not primarily fat loss, but usually a reduction in water retention, bloating, and inflammation.”

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After a month, Davidson said weight loss, if done correctly, will be slow and steady.

He strongly advises against trying to lose weight too quickly.

“Most strategies that accelerate weight loss faster than the recommended 2 to 3 pounds a week after the initial removal of retention are devastating to the metabolism. They require large amounts of stress to be put on the body,” Davidson said.

Shannon Wilsey of San Francisco said she experienced many of these complications. Her insomnia resulted in a loss of appetite, and combined with the death of a family member, she says she was not interested in eating for four to five months. When she started eating again, she consumed very little food.

“My body quickly ate through fat and most of my muscle, and I deteriorated quickly. The stress on my body was great,” she said.

Once she was able to start eating again, Wilsey said she had to do so very slowly.

“I have never regained the muscle mass I had as a child or swimmer. I have suffered significant hair loss, and my digestive tract can’t easily handle certain spicy or hard-to-digest foods.” 

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Is there ever a good reason to lose weight quickly?

“Rapid weight loss is usually only beneficial to those who are classified as obese or morbidly obese,” said Josefsberg, “and are suffering the health risks associated with that condition.”

She said it is best to be supervised by a physician while on extremely low-calorie, rapid weight loss diets so that side effects and dangers like electrolyte imbalances can be monitored. 

Boling agreed it may be beneficial to have a patient lose weight under a physician’s supervision quickly over the short term. 

“It motivates patients to continue diet and exercise programs when they see results quickly. It is less likely that they will relapse to old habits and more likely that they will reach their goal weight,” she said.

Even in very low-calorie diets, however, it’s critical that adequate nutrition and vitamins are provided.