The IU diet is an extreme eating plan made famous by Korean pop star IU (Lee Ji-eun), consisting of just one apple, two sweet potatoes, and a protein shake per day. It totals roughly 300 to 500 calories, far below what any adult needs to function safely. IU revealed this plan on the Korean TV show Night of TV Entertainment in 2013, saying it helped her lose about 11 pounds (5 kg) in five days after gaining weight while filming a drama.
The diet went viral as the “IU diet challenge,” with fans and social media users attempting to replicate it. But the plan is nutritionally dangerous, and even IU herself has spoken about her struggles with disordered eating in the years since.
What You Eat on the IU Diet
The diet breaks down into three small meals across the day. Breakfast is one apple, lunch is one or two sweet potatoes, and dinner is a protein powder shake. There is no flexibility, no additional snacks, and no variation. The total calorie count lands somewhere between 300 and 500 calories depending on the size of the sweet potatoes and the protein powder used.
For context, most adults need a minimum of 1,200 to 1,500 calories per day just to cover basic bodily functions like breathing, circulation, and maintaining organ tissue. The IU diet provides roughly a quarter to a third of that floor. It contains almost no fat, very little protein beyond the shake, and is missing entire categories of nutrients: calcium, iron, zinc, B vitamins, and adequate fiber from varied sources. You would get some vitamin A and vitamin C from the sweet potatoes and apple, but virtually nothing else your body requires in meaningful amounts.
Why It Causes Rapid Weight Loss
Losing 11 pounds in five days is not primarily fat loss. At this level of calorie restriction, the body sheds water weight first. Glycogen, the stored form of carbohydrates in your muscles and liver, binds to water molecules. When you drastically cut calories, your body burns through glycogen stores quickly, releasing that water. This accounts for most of the dramatic initial drop on the scale.
After the water weight, the body starts breaking down muscle tissue for energy because there isn’t enough protein or total calories to preserve it. Fat loss does occur, but it happens alongside significant muscle loss. The result is a lower number on the scale that masks real damage to your body composition. You end up lighter but with less muscle mass, which makes regaining weight afterward even easier.
Health Risks of Eating This Few Calories
Diets this extreme carry serious physical and psychological consequences. When the body doesn’t receive enough calories, it enters a conservation mode, slowing its metabolic rate to match the reduced energy supply. Research consistently shows that this metabolic slowdown can persist long after the diet ends, meaning your body burns fewer calories at rest than it did before you started. In some cases, metabolic rates decline and fail to fully rebound.
The specific risks include:
- Muscle loss: Without adequate protein and calories, the body breaks down its own muscle tissue for fuel. This further lowers your resting metabolic rate.
- Heart problems: Extreme calorie restriction can cause irregular heart rhythms, low blood pressure, and even loss of heart muscle tissue.
- Blood sugar swings: Eating so little causes blood sugar to fluctuate unpredictably, leading to dizziness, fainting, and difficulty concentrating.
- Dehydration: With so little food coming in, fluid balance suffers quickly.
- Mood and energy collapse: People on extreme diets commonly feel sluggish, moody, anxious, depressed, and irritable.
Perhaps the most damaging long-term consequence is the cycle it creates. Rapid weight loss followed by inevitable regain, known as yo-yo dieting, progressively slows your metabolism with each cycle. Every round makes it harder to lose weight and easier to gain it back.
Nutrient Gaps in This Plan
Three foods cannot cover what your body needs. The IU diet is nearly devoid of healthy fats, which are essential for hormone production, brain function, and absorbing certain vitamins. It contains no meaningful source of calcium for bone health, no iron-rich foods for oxygen transport in your blood, and negligible amounts of zinc, which supports immune function and wound healing.
The protein shake provides some amino acids, but one serving per day falls well short of the minimum needed to maintain muscle tissue, especially when total calories are this low. B vitamins, which are critical for energy metabolism and nervous system function, are largely absent. Even a few days on this plan would begin depleting your body’s stored reserves of several key nutrients.
IU’s Own Experience With Disordered Eating
IU has been open about her difficult relationship with food and body image throughout her career. The 2013 diet was not an isolated event but part of a broader pattern of restrictive eating tied to the intense appearance pressures of the K-pop industry. She has spoken publicly about struggling with anxiety and eating disorders, framing her past dietary habits as something she needed to move beyond rather than something to emulate.
In more recent years, IU has shifted toward healthier habits, including regular exercise and more balanced eating. The gap between the viral “IU diet challenge” and her actual experience with it is significant. What spread online as a quick weight loss hack was, for her, part of a painful cycle she has worked to break.
Why Social Media Diet Challenges Are Misleading
The IU diet gained traction because the results sound dramatic: 11 pounds in five days. But that number reflects water and muscle loss on a timeline that is impossible to sustain and harmful to attempt. Any weight lost this way returns quickly once normal eating resumes, often with additional pounds because of the metabolic damage done during the restriction period.
K-pop diet culture more broadly tends to emphasize appearance standards over health, which puts younger fans especially at risk. Research has found that using sociocultural appearance ideals as weight loss motivation increases the likelihood of developing disordered eating behaviors, particularly among adolescents. A diet built around three foods and a few hundred calories per day is not a weight loss strategy. It is a form of food deprivation that happens to produce temporary changes on a scale.
Sustainable weight management looks nothing like this. It involves eating enough to support your activity level, getting protein at every meal to preserve muscle, including a wide variety of fruits, vegetables, whole grains, and healthy fats, and losing weight gradually, typically one to two pounds per week at most. The speed is less impressive. The results actually last.