intermittent Fasting

 Intermittent Fasting

Intermittent fasting can mean several things, but in a broad sense it is a schedule of when you eat and when you fast.  Many people choose to eat only within an eight hour window each day and fast for the other 16 hours. An example of this would be waking at 6 am but waiting to eat until 10 am and then having your last meal at 6 pm. 

Intermittent fasting (IF) has gained popularity in recent years as a weight loss strategy, with proponents claiming it can also improve overall health and longevity. The theory behind IF is that after your body has burned through its sugar stores from the last meal eaten then the body switches to burning fat causing weight loss. However, while IF may work well for some people, it may not be the best approach for everyone, especially women.  In fact, there is evidence to suggest that IF can be harmful to women's hormones and overall health.  Let's take a closer look at why.

Stressful for the Body

Intermittent fasting can be stressful for the body, particularly for women. This is because women's bodies are more sensitive to changes in calorie intake and may perceive IF as a stressor.  When the body perceives stress, it triggers the release of cortisol, a hormone that can negatively impact the body if it remains elevated for long periods.  Out of 71 studies found in Harvard’s database for intermittent fasting, only 13 mention or include women in the dataset at all.  None of the controlled studies focus on the female population.  Of the 13 studies that include women, the results showed a 50 percent INCREASE in cortisol levels, and a DECREASE in insulin sensitivity as a result of intermittent fasting.1,2 

Increases Cortisol Levels

When you do not eat, your body will make fuel by catabolizing your muscles to raise your blood sugar, which requires the adrenals to increase cortisol production. 

When cortisol levels are consistently elevated, it can lead to inflammation, insulin resistance, and weight gain.  In women, cortisol can also lead to imbalances in other hormones, such as estrogen and progesterone, which can disrupt the menstrual cycle and lead to other reproductive health issues.

Decreases Insulin Sensitivity

IF can also decrease insulin sensitivity, which can lead to high blood sugar levels and increase the risk of developing type 2 diabetes.  In women, insulin resistance can also impact fertility and increase the risk of polycystic ovary syndrome (PCOS), a condition that affects the hormonal balance and reproductive health.

Hard to Eat Enough Calories

It can be hard to eat enough calories while practicing IF, particularly for women who require more calories than men due to differences in body composition and hormonal balance.  When the body is not getting enough calories, it may go into a state of energy conservation, slowing down metabolism and burning fewer calories which would be counterproductive to weight loss.

Depletes Your Body’s Mineral Stores

Finally, IF can deplete the body's mineral stores, leading to nutrient deficiencies and other health issues. This is because when the body is not getting enough calories, it may also not be getting enough essential vitamins and minerals, which are necessary for optimal health and hormonal balance.

Cost, Time Commitment, and Degree of Lifestyle Modification

In terms of cost, IF may be more affordable than other weight loss programs, as it does not require any special products or supplements. The time commitment needed for IF is not necessarily higher than other programs. However, it can require a significant degree of lifestyle modification, particularly for women who may need to balance the demands of work, family, and other responsibilities. The time constraints and planning of when you will eat will be significantly different than to what you were previously accustomed.

Family Friendliness and Health Considerations

IF may not be family-friendly, as it can be difficult to stick to a strict eating schedule when others in the household are not practicing IF. Additionally, it may not be appropriate for individuals with certain health conditions, such as diabetes or eating disorders, and should be avoided or approached with caution in these cases.

Sustainability of Weight Loss After Stopping Diet and Support Provided

Finally, while IF may lead to initial weight loss, it may not be sustainable in the long run, particularly if it leads to metabolic damage or hormonal imbalances. Additionally, support from a healthcare provider or registered dietitian may be necessary to ensure that IF is approached in a safe and healthy manner.

Hormone-Friendly

IF may be one of the least hormone-friendly eating styles in our culture for women specifically.  Most of the research for IF that showed positive results was done in men. Even though this opinion may seem controversial at this time, IF can be devastating for women’s hormones long-term, especially if the woman is in her child-bearing years. IF after menopause has not been widely studied.

Conclusion

In the short-term, intermittent fasting can be effective for weight-loss.  However, the long-term effects can be overall damaging, therefore we cannot recommend it as a weight-loss strategy.  

1 Yuko Nakamura, Brian R. Walker & Toshikazu Ikuta (2016) Systematic review and meta-analysis reveals acutely elevated plasma cortisol following fasting but not less severe calorie restriction, Stress, 19:2, 151-157, DOI: 10.3109/10253890.2015.1121984

2 Kim KK, Kang JH, Kim EM. Updated Meta-Analysis of Studies from 2011 to 2021 Comparing the Effectiveness of Intermittent Energy Restriction and Continuous Energy Restriction. J Obes Metab Syndr. 2022 Sep 30;31(3):230-244. doi: 10.7570/jomes22050. PMID: 36177730; PMCID: PMC9579470.