Intermittent fasting, also known as IF, has become popular due to its potential health benefits as a dietary pattern. Some IF enthusiasts have reported experiencing increased energy levels, weight loss, and improvements in metabolic health. (1) However, intermittent fasting may not be suitable for everyone. Before embarking on an IF regimen, it’s essential to consider a few health factors to determine if it’s the right choice for you.
Research indicates that individuals with specific health conditions, such as those affecting digestion, blood sugar levels, or individuals in particular life stages, should approach intermittent fasting cautiously. (4) Let’s delve into the scientifically backed considerations to help you assess if intermittent fasting aligns with your health and lifestyle.
Medical Conditions and Medications: Who Should Avoid Intermittent Fasting?
Prior to adopting intermittent fasting, it’s crucial to evaluate your medical history and current medication regimen. Particularly, individuals with diabetes, kidney stones, or gastroesophageal reflux disease should approach fasting with caution and seek personalized advice before initiating the practice. (4)(5)
Moreover, individuals on medications for heart disease, diabetes, high blood pressure, or medications that necessitate food intake for proper absorption should exercise caution with intermittent fasting. It’s essential to recognize that individuals with a history of eating disorders should refrain from intermittent fasting as any form of diet plan can trigger unhealthy behaviors related to food restriction and binge eating. (7)
Health Conditions That Might Make Intermittent Fasting a Bad Idea
If you are taking medications for health conditions such as heart disease, diabetes, high blood pressure, or medications like insulin and blood thinners that require regular food intake for proper absorption, intermittent fasting may not be suitable for you. ( 6)
Here are other health conditions that might deem intermittent fasting unsuitable for you:
- Diabetes: Fasting can impact blood sugar levels, leading to risky drops or unpredictable spikes. (4)
- Kidney Stones: Fasting may increase the risk of stone formation by affecting hydration status and dietary intake. (5)
- Underweight Individuals: Fasting can lead to additional weight loss, necessitating medical supervision and regular healthcare assessments. (8)
- History of Eating Disorders: Fasting may trigger unhealthy eating behaviors, rendering it unsafe for individuals with past or current eating disorders. (7)
The Impact of Intermittent Fasting on Metabolism
One of the most discussed benefits of intermittent fasting is its influence on metabolism. Studies suggest that fasting initiates fat-burning through a process known as ketosis, where the body utilizes fat for energy in the absence of carbohydrates. (1)
Additionally, intermittent fasting may enhance insulin sensitivity, potentially lowering the risk of developing type 2 diabetes by reducing blood sugar levels and promoting better glucose control. (9)
Nevertheless, research indicates that when compared to other calorie-controlled diets, fasting does not necessarily lead to more pronounced weight loss than other forms of calorie-restricted diet plans. (10)
This implies that if intermittent fasting is not suitable for you, any diet that resonates with you can still assist you in achieving your weight loss objectives.
Another metabolic advantage of intermittent fasting is autophagy, a process of cellular repair and regeneration that occurs with any form of caloric restriction. (11) This process is associated with longevity and may safeguard against age-related ailments by eliminating damaged cells. (11)
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Hormonal Effects: Why Fasting May Be Different for Women
Women’s bodies are highly responsive to changes in calorie intake, which is why intermittent fasting can influence female hormones like estrogen and progesterone. (12)
Studies indicate that prolonged fasting could disrupt women’s reproductive hormone balance, potentially resulting in irregular menstrual cycles and unpleasant symptoms. (12) Notably, women attempting to conceive should avoid long fasting periods as caloric restriction can negatively impact fertility. (12)
During pregnancy or breastfeeding, fasting may lead to nutrient deficiencies and inadequate calorie intake, affecting both maternal and infant health. (13) Women in these stages should consult their healthcare team before initiating intermittent fasting.
Even outside of pregnancy, women with hormonal imbalances such as polycystic ovary syndrome (PCOS) should exercise caution with fasting as it may exacerbate symptoms. (13)
Ultimately, research suggests that women may benefit more from shorter fasting windows, like 12 to 14 hours, as opposed to a more stringent 16-hour schedule. (14)
About the Experts:
Caroline Thomason is a dietitian and diabetes educator, blending her passion for nutrition with making health information easily understandable. With 12 years of experience in the field, she has been published in over 40 publications, serves as a CPG consultant and advisor, a speaker, broadcast spokesperson, and recipe developer.
Joanna Gregg, RD is a food data curator at MyFitnessPal. She holds a bachelor’s degree in Nutrition from Georgia State University and a Master’s degree from The University of Nebraska.
Cortisol and Stress: The Science of Fasting and Stress Response
Intermittent fasting can impact cortisol levels, a hormone responsible for regulating the body’s stress response. (15) Long fasting periods may increase cortisol production, especially in individuals already experiencing stress or lack of sleep. (15) Elevated cortisol levels are associated with weight gain, particularly in the abdominal area, counteracting the weight loss benefits of fasting. (16)
Moreover, high cortisol levels might trigger stress eating once the fasting period ends, leading to a cycle of overeating followed by restrictive fasting. (17) This represents a form of disordered eating, and if you find yourself in this pattern, fasting may not be suitable for you. (17)
Overall, if you are prone to stress or struggle with managing stress-induced cravings, intermittent fasting may not be the best choice for you.
Blood Sugar Sensitivity: Who Should Be Careful?
Individuals with blood sugar concerns, such as diabetes or hypoglycemia, need to approach intermittent fasting with caution. (4) While fasting may enhance insulin sensitivity, it can pose risks for those with diabetes as prolonged fasting may lead to dangerously low blood sugar levels. (9)
Especially if you are taking insulin or other medications affecting blood glucose levels, fasting may heighten the risk of hypoglycemia, which can result in severe symptoms like dizziness, confusion, or fainting. (18)
Even for individuals without diabetes, prolonged fasting can lead to blood sugar drops, causing irritability or general fatigue. (19) If you have a blood sugar-related condition, consider shorter fasting periods or consult a healthcare professional to determine the safest approach for you.
The Bottom Line: Is Intermittent Fasting Right for You?
While intermittent fasting is renowned for its potential metabolic health benefits, it may not be suitable for everyone. Before diving in, consider how fasting may impact your hormones, metabolism, stress levels, and blood sugar regulation.
Before adopting any new diet, consult a healthcare provider like a dietitian or your physician. If fasting proves unsuitable for you, there are numerous nutrition plans available to assist you in achieving your goals instead.
If you opt to try intermittent fasting, explore the Intermittent Fasting Tracker within the MyFitnessPal app.
Frequently Asked Questions
Does intermittent fasting cause or worsen gastroesophageal reflux disease (GERD)?
The research on intermittent fasting is inconclusive. Some limited studies suggest that GERD symptoms may improve with fasting. (20)
What should my first meal be when intermittent fasting?
When breaking your fast during intermittent fasting, opt for a balanced meal providing essential nutrients. Meals centered on whole foods offering lean protein, complex carbohydrates, and healthy fats are recommended.
What can I drink in the morning while intermittent fasting?
If you aim to maintain your fast, stick to calorie-free beverages like water, black coffee, or tea.
How MyFitnessPal Can Help
Whether you are already engaged in intermittent fasting or are curious about its potential health advantages, MyFitnessPal’s Premium Intermittent Fasting Tracker feature can be beneficial. You can choose from three fasting patterns based on your lifestyle and objectives:
12:12 – 12-hour fasting, 12-hour eating window. This pattern aligns meals with your circadian rhythm.
14:10 – 14-hour fasting, 10-hour eating window. This pattern encourages regular meals and reduced snacking throughout the day.
16:8 – 16-hour fasting, 8-hour eating window. This pattern typically involves skipping either morning or evening eating times.
You can track your daily fasting periods alongside meals, water intake, and exercise in your diary. Ready to give it a shot? Initiate a free MyFitnessPal Premium trial now.
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Table of contents
- Medical Conditions and Medications: Who Should Avoid Intermittent Fasting?
- Health Conditions That Might Make Intermittent Fasting a Bad Idea
- The Impact of Intermittent Fasting on Metabolism
- You might also likeIs There A Best Intermittent Fasting Window For Belly Fat Loss? >
- Hormonal Effects: Why Fasting May Be Different for Women
- About the Experts:
- Cortisol and Stress: The Science of Fasting and Stress Response
- sensitivity-who-should-be-careful">Blood Sugar Sensitivity: Who Should Be Careful?
- The Bottom Line: Is Intermittent Fasting Right for You?
- Frequently Asked Questions
- Does intermittent fasting cause or worsen gastroesophageal reflux disease (GERD)?
- What should my first meal be when intermittent fasting?
- What can I drink in the morning while intermittent fasting?
- How MyFitnessPal Can Help
- Vocabulary List:
- How much do you know?
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