Intermittent Fasting: Safe or Risky?

20 Apr 2026

Source: Freepik (www.freepik.com)

In Indonesia, the prevalence of obesity has been rising over the past few years. Survey data from Indonesia show an increase in adult obesity rates from 21.8% to 23.4%. Obesity is a chronic medical condition characterized by an excessive amount of body fat. This is an alarming issue that must be taken into consideration, as it can lead to complications such as type 2 diabetes, high blood pressure, stroke, and other conditions. 

Many people who are overweight have tried different weight-loss methods, including intermittent fasting (IF), which focuses on when you eat. It alternates between fasting and eating periods 

This study aims to examine the safety of intermittent fasting as a weight-loss method among adults.

What is Intermittent Fasting?

So, what exactly is intermittent fasting?

Simply put, intermittent fasting (IF) is not really a “diet”, it’s more about when you eat, not what you eat. Instead of focusing on cutting certain foods, IF is about managing the timing between eating and fasting periods.

Intermittent fasting is an eating pattern where individuals reduce or avoid calorie intake during certain periods, followed by periods of normal eating. Think of it as giving your body a schedule: there are times when you eat normally and times when you don’t eat at all (or consume very minimal calories). During fasting periods, calorie intake can drop very low, sometimes even close to zero, depending on the method used.

Intermittent fasting is also considered an alternative to traditional calorie restriction. This approach is more flexible compared to diets that require reducing calorie intake every day. The duration of fasting can vary, from just a few hours in a day to a full 24-hour fast, depending on the method chosen.

Types of Intermittent Fasting

Now, here’s where it gets more interesting, there isn’t just one way to do intermittent fasting. Here are some of the most common methods: 

  • 16/8 Method ( Time-Restricted Feeding)
    The first method is the 16/8 method. It limits eating to a specific time window (usually around 8–12 hours), with the remaining hours spent fasting. 
  • 5:2 Method
    Another popular approach is the 5:2 method, where people eat normally for five days and significantly reduce calorie intake (around 0–500 kcal) on the other two days.
  • Alternate-Day Fasting
    There’s also alternate-day fasting (ADF), where fasting days are alternated with normal eating days.

Even though the methods look different, they all follow the same core idea: alternating between fasting and eating periods.

Health Benefits of Intermittent Fasting

Intermittent fasting offers several health benefits, especially for those looking to improve their overall well-being.  

  • Effective for Weight Loss
    A review of 10 clinical trials with 701 participants found that it significantly reduced body weight, BMI, and waist circumference in adults with overweight or metabolic syndrome. The reason is simple: intermittent fasting helps people eat fewer calories without counting them every day.
  • Improves Heart Health
    Beyond weight loss, intermittent fasting also benefits heart health. It significantly lowers LDL-C (bad cholesterol), an important risk factor for heart disease and stroke, with high-quality evidence supporting the findings.
  • Better Blood Sugar Control
    For those concerned about diabetes, intermittent fasting shows promising results. A study of 1,441 people with type 2 diabetes found it reduced HbA1c (average blood sugar over 3 months) by 1.85%, helping reduce the risk of complications. Overall, it can be an effective strategy for managing type 2 diabetes.
  • Reduces Inflammation
    Research found that intermittent fasting significantly reduced interleukin-6 (IL-6) , which is a key marker of inflammation in the body. The evidence for this benefit was also rated as HIGH quality.

Risks and Solutions of Intermittent Fasting 

While intermittent fasting (IF) offers many health benefits, it’s important to understand the risks and how to manage them. Here are some common risks and their solutions: 

  • Risk of Drastic Calorie Reduction
    IF limits eating windows, which can significantly reduce calorie intake, sometimes close to zero. If not managed well, this can lead to low energy.
    Solution: Make sure you get enough nutrients during eating periods and focus on nutrient-dense foods.
  • Challenges in Metabolic Adaptation
    At first, the body may have difficulty adapting to changes in eating schedules, especially with extreme methods such as a full 24-hour fast.
    Solution: Choose a method that fits your lifestyle. The 16/8 method is recommended for beginners because its flexible eating window (8–12 hours) makes it easier to follow.
  • Risk of Hypoglycemia in Diabetics
    For individuals with type 2 diabetes, sudden changes in eating patterns significantly lower blood sugar levels, and while IF can reduce HbA1c, the risk of fluctuations remains.
    Solution: IF should be done under medical supervision. Consult a healthcare professional to adjust medication or insulin and prevent complications.
  • Lack of Social and Psychological Flexibility
    Traditional diets can feel restrictive because they limit certain foods every day, which may create psychological pressure.
    Solution: Take advantage of IF’s flexibility. It focuses on when you eat, not what you eat. 

Conclusion: So, is it safe or risky?  

Overall, intermittent fasting is a popular weight loss method that focuses on when you eat and supports weight loss, heart health, blood sugar control, and reduced inflammation. 

So, is it safe? For most adults, the answer is yes, intermittent fasting is a safe and effective approach. But it’s not completely risk-free. Some people may experience low energy, difficulty adapting, blood sugar changes, and social or psychological challenges, especially those with certain health conditions. 

In other words, intermittent fasting works safely when it’s done properly. Choose what works for you, eat well, and listen to your body health. 

References:

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