Effects of Intermittent Fasting — Weight Loss, Metabolic Improvement, and the Korean Medicine Perspective
Table of Contents
Recently, the number of patients in the clinic asking, "Doctor, does intermittent fasting really work?" has increased significantly. On YouTube, they say you only need to fast for 16 hours and the weight just melts off, but when they actually try it, they end up overeating more and the number on the scale stays the same, leaving them frustrated. Since I get the same questions every week, today I'll break down the research data along with the Korean medicine perspective.
![A 2×3 or 3×2 matrix grid arranging 6 types of intermittent fasting methods. Each cell shows a clock image with the ratio displayed (16:8, 5:2, 14:10, 23:1, 18:6, 20:4).]](/api/files/assets/2026-06/8fa273d8.jpg?sig=4a3ed267f287fb7c7b3099fdc84dbfd44e1429879167a499f01fe3625e52e2d9)
![A scene of a Korean medicine clinic. The doctor and patient sitting face to face, with the patient holding a snack in their hand. A warm, trustworthy atmosphere. The doctor is smiling and explaining in a helpful pose, the patient has an expectant expression.]](/api/files/assets/2026-06/624b11dd.jpg?sig=a77f510ad94941a6b11b8f82d6e6d0a178cedcd1269f1be01cd44894ac293d72)## Intermittent Fasting: It's Ultimately a Question of "When You Eat"
According to the Korean Society for Nutrition, intermittent fasting is defined as "maintaining a fasting state for a set period by establishing a certain time schedule." Rather than what you eat, the key is when you eat and when you don't eat—in other words, securing fasting time. The most common method is 16:8 (fasting for 16 out of 24 hours per day, eating within 8 hours), and on a weekly basis, 5:2 (eating normally for 5 days, significantly reducing calories for 2 days) is commonly followed. Other variations include 23:1 (1 meal per 1 day), 14:10, 18:6, and so on. For beginners, I typically recommend starting with 14:10.
The Real Reason You Lose Weight Is Calories
Here's where many people get confused. They think, "If I just fast for 16 hours, I'll lose weight automatically." However, according to data from the Korean Diabetes Association, the main advantage of intermittent fasting ultimately comes down to weight loss from reduced food intake. If you normally eat 1,800 kcal per day but cut down to one meal of 600~800 kcal, you're cutting about 1,000 kcal per day, so weight loss is inevitable.
In an article summarizing a 2014 meta-analysis, some studies reported weight loss of approximately 324% of body weight over 38 weeks. The numbers look appealing, but when high-quality studies are combined, the conclusion that prevails is intermittent fasting does not result in significantly greater weight loss than other low-calorie diets when calories are equal. In one analysis, the intermittent fasting group only lost an additional 0.33 percentage points (0.33 kg for a 100 kg person) compared to the other diet group. The time restriction itself is not magic.
![Left side (❌ Wrong approach): After 16 hours of fasting, swayed by confidence, with cakes, fried foods, ramen, and other high-fat foods piled on a table floating around. Right side (✅ Correct approach): A neat plate with "a]](/api/files/assets/2026-06/567b66cb.jpg?sig=0e3f6e3d7b4d83ce6a89d33fd3af617adc77ec94491e53949c1353371fc33592)
How do actual patients change
In the consultation room, I see patients split into two groups. One group adheres well to 16:8 and eats slightly less than usual even within the 8-hour eating window. For these individuals, weight loss occurs, and as a following change, a trend of stabilizing blood sugar, blood pressure, and lipid levels is observed. This is an area where it can be helpful.
The other group consists of those who binge eat during the eating window, thinking, "I fasted for 16 hours anyway." In this case, the total calorie intake does not decrease, so the number on the scale remains the same, and they instead complain of gastrointestinal discomfort due to nighttime binge eating. It turns out that what and how much is eaten during the 8 hours, rather than the fasting time, determines the result.
How Baekrokdam Korean Medicine Clinic views this
From a Korean medicine perspective, intermittent fasting is not a simple diet method, but is closer to a dietary pattern that secures rest time for the Spleen and Stomach (脾胃). Our bodies spend energy processing food all day; when a consistent fasting period is maintained, the Spleen and Stomach get a chance to rest, and for many, the digestion and absorption rhythm becomes organized.
However, not all constitutions react the same way. For those with a Qi Deficiency (氣虛) constitution who tire easily and have cold hands and feet, long periods of fasting tend to lead to lethargy and headaches. Conversely, for those with a lot of Phlegm-Dampness (痰濕) and strong appetites, the method of reducing the eating window tends to be a good fit. That is why I do not say "16 hours is the answer." I look at the constitution and life rhythm together and recommend starting slowly from 14:10 and gradually increasing. I also inform them that research on long-term effects and safety is still limited.
Action points you can try today
You do not have to start grandly. This is advice I frequently give in the consultation room.
- For the first week, try 14:10. Finish dinner by 8 PM, and have your first meal at 10 AM the next day. Start by observing if your body adapts to this level.
- During the 8-hour eating window, fill it mainly with protein and vegetables. If you binge on sweet foods as a reward for enduring the fast, the effect disappears.
- If dizziness, palpitations, or headaches recur during fasting, stop immediately and consult a nearby medical professional.
- If you are pregnant, breastfeeding, or taking diabetes or blood pressure medication, professional consultation is essential before self-fasting.
- Try recording changes in waist circumference and post-meal condition along with the scale number. The trend becomes more visible.
Intermittent fasting is certainly a helpful tool for those it suits. However, the starting point must differ depending on constitution, lifestyle patterns, and underlying diseases, and there are truly many people who end up with binge eating and lethargy by overdoing it alone. At Baekrokdam Oriental Medicine Clinic, we provide a seamless process from constitutional diagnosis and dietary pattern checks to the prescription of Baekrok Gambi-jung tablet herbal medicine. If you have failed two or three times on your own, please come for a light consultation. We will help you resolve the parts that felt frustrating.
