AKMU's Lee Suhyun says she regretted losing 30 kg — here's the extreme diet she called a 'last resort'

Lee Suhyun of K-pop duo AKMU has opened up about the health problems she experienced while losing 30 kilograms through extreme dietary restrictions. In her effort to shed weight quickly, she cut sodium intake so severely that she lost energy and could barely detect her own pulse.

In a video posted Tuesday to her YouTube channel "Lee Suhyun Official," Lee recalled a period when she limited her meals to sweet potatoes, regular potatoes, chicken breast and egg whites. "After about a week of eating that way, my stomach started hurting. I had no energy — I could feel myself becoming genuinely unhealthy," she said, describing the regimen not as a diet but as a "last resort."

She also revealed that "for nearly half the year, I couldn't feel my pulse at all," and said her condition improved after a coach advised her to increase her sodium intake. She added that she subsequently managed her weight for more than two years by combining a health-focused diet with regular exercise.

Salt is essential too — what happens when sodium runs low

Salt is typically one of the first things people cut when they start dieting. Excessive sodium intake can raise blood pressure and increase fluid retention, making a low-sodium diet a widely recommended component of healthy eating. Sodium is, however, an essential electrolyte involved in the body's fluid balance, nerve signal transmission and muscle contraction.

Sodium is distributed primarily in the fluid outside cells, where it regulates osmotic pressure. It helps ensure that water is properly distributed throughout the body and plays a role in maintaining blood volume and blood pressure. Sodium is also critical to the process by which nerve cells transmit electrical signals and muscles contract.

According to MedlinePlus, the medical information service run by the US National Library of Medicine, a condition in which blood sodium levels fall below the normal range is called hyponatremia. It is generally defined as a blood sodium concentration below 135 mmol/L and can cause fatigue, headaches, nausea and muscle cramps. In severe cases it can lead to impaired consciousness or seizures.

However, blood sodium levels are regulated not only by how much salt a person adds to food but also by fluid intake, kidney function, hormones and medications. Hyponatremia often develops not from an absolute shortage of sodium in the body but from a disruption in the balance between water and sodium.

Combining intense exercise that produces heavy sweating with extreme food restriction or excessive water consumption can affect the body's fluid and electrolyte balance. Caution is also warranted when sodium is lost through vomiting, diarrhea or the use of diuretics.

WHO recommends that adults consume less than 2,000 mg of sodium per day — the equivalent of less than 5 grams of salt, or just under one small teaspoon. The guideline is intended to reduce the risk of high blood pressure and cardiovascular disease by curbing excessive sodium intake. The key to a healthy low-sodium diet lies not in eliminating salt entirely but in reducing the excess sodium that most people consume daily.

'Couldn't feel my pulse' — how extreme food restriction affects the heart

The pulse irregularities Lee described are an important physical warning sign to watch for during weight loss. A weak pulse at the wrist or an abnormally low heart rate can stem from a range of causes, including low blood pressure, dehydration, nutritional deficiency and cardiac arrhythmia.

Prolonged extreme caloric restriction can place strain on the cardiovascular system. The body reduces energy expenditure to adapt to insufficient fuel, and in cases of severe malnutrition, resting heart rate can drop abnormally low — a condition known as bradycardia — and blood pressure may also fall.

A 2023 paper published in Focus, an academic journal of the American Psychiatric Association, noted that bradycardia and low blood pressure are commonly observed in patients who are malnourished from restrictive eating. Orthostatic hypotension — a drop in blood pressure when changing posture — can cause dizziness and fainting, and the risk of arrhythmia rises when electrolyte imbalances are also present.

The UK's National Institute for Health and Care Excellence similarly recommends evaluating the need for an electrocardiogram when a patient shows rapid weight loss, excessive exercise, bradycardia, low blood pressure, muscle weakness or electrolyte imbalances.

In Lee's case, no test results — such as blood sodium levels or heart rate measurements — were made public, so the medical cause of her symptoms at the time cannot be confirmed. That said, anyone who experiences persistent fatigue or pulse irregularities while drastically cutting food intake should have their blood pressure, heart rate and electrolyte levels checked.

Prompt medical attention is particularly important if dizziness recurs or is accompanied by fainting, chest pain, shortness of breath or severe palpitations. Because treatment depends on the underlying cause, people should also avoid trying to resolve symptoms on their own by consuming large amounts of salt or water.

More than two years to lose 30 kg — why dietary balance matters more than the number on the scale

After abandoning her extreme diet, Lee said she shifted to an eating pattern that balanced carbohydrates, protein and vegetables. In the video, she shared a meal plan built around brown rice, chicken breast, sweet potatoes and vegetables, and said the full 30-kilogram loss took more than two years.

The key to long-term weight management is supplying the body with adequate nutrients while controlling caloric intake. Carbohydrates are the primary energy source for the brain and muscles, while protein is needed to maintain muscle tissue. Fat also plays a role in cell membrane structure, hormone production and the absorption of fat-soluble vitamins.

The 2026 clinical guidelines published by the American Diabetes Association in the journal Diabetes Care said that people undergoing intentional weight loss should have their nutritional status checked regularly to prevent deficiencies in protein and micronutrients.

A diet that controls overall caloric intake while including a balanced mix of vegetables, whole grains and quality protein sources is generally recommended. Whole grains such as brown rice and oats supply dietary fiber, while eggs, fish, lean meat and legumes help meet protein needs. Healthy fats from nuts, olive oil and fish should also be consumed in appropriate amounts.

Sodium intake should likewise be managed in the context of the overall diet. People who frequently eat processed foods, broth-based dishes or salty banchan (Korean side dishes) can benefit from reducing their sodium consumption. Those who eat very little while exercising heavily, however, should also monitor their caloric, fluid and electrolyte intake.

Rapid weight loss can also work against long-term maintenance. The US Centers for Disease Control and Prevention notes that people who lose weight gradually — roughly 0.45 to 0.9 kilograms per week — are generally more likely to keep the weight off than those who lose it more quickly.

Regular physical activity and adequate sleep are as important as diet in managing weight. Increasing activity through aerobic exercise such as walking or cycling, combined with strength training to preserve muscle during the weight-loss process, is beneficial.

If fatigue worsens significantly during a diet, exercise capacity drops sharply, or dizziness and changes in heart rate appear, it is time to reassess food intake and exercise intensity. Paying attention to the body's warning signals — not just the number on the scale — is the foundation of safe weight management.