Does Intermittent Fasting Lower Thyroid Function?

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Hypothyroidism and intermittent fasting; is it safe and effective? Having a thyroid that doesn’t operate at its optimal level can be an obstacle that makes it difficult for many to lose weight. Periodic fasting could be helpful for you. Is it safe? This is what the evidence suggests and all the information you need to begin your journey effectively!

What Is Hypothyroidism?

If you suffer from a condition known as hypothyroidism or an underactive thyroid, it is likely that you do not require much of an explanation. The Mayo Clinic outlines Hypothyroidism as a state in which the thyroid gland doesn’t generate adequate amounts of essential hormones. If you have issues related to Hypothyroidism, this link contains useful information on how to cope.

The thyroid has a major influence on numerous bodily operations. If the thyroid does not produce enough hormone, you might suffer from a combination of indications, including exhaustion, low body temperature, dry and brittle hair and skin, hair thinning, slight weight increase, decreased appetite, absentmindedness, frequent numbness in the extremities, irregularity, Carpal Tunnel Syndrome, heavier menstrual flow and cramps, touchiness, depression, or an enlargement of the thyroid (goiter).

At first, some people may not realize anything is wrong; however, if the hypothyroid condition is not treated, there may be long-term effects. This can include being overweight, aching joints, the inability to conceive, and cardiovascular illness.

Who Is at Risk for Hypothyroidism?

Female individuals are more likely to experience hypothyroidism than males. It has been estimated that approximately 2-3% of people in the United States have hypothyroidism, while around 10-15% have mild hypothyroidism. About 8% of females and 3% of males have a mild form of hypothyroidism, particularly those over 55 years of age in women.

What Is Intermittent Fasting?

IF is a style of eating that concentrates on the timing of food intake and abstaining from food instead of centering on what food items are consumed.

Rather than adhering to a detailed diet or concentrating on which foods to get rid of or prevent, Intermittent Fasting provides you with a specific ‘time frame’ for when to eat and fast to maximize how your body makes use of food. A lot of people enjoy this kind of diet as it provides them with greater freedom when attempting to shed pounds.

People may utilize intermittent fasting for many different reasons. Some employ it to slim down or keep off the weight they have already shed. Some people employ it to reduce inflammation, enhance cognitive performance, promote insulin responsiveness, or enhance longevity. Research has demonstrated that Intermittent Fasting can be utilized as an effective method for weight reduction.

How Do I Do Intermittent Fasting?

There are numerous strategies for committing to Intermittent Fasting. One main approach concentrates on limits related to time. You consume food within certain windows of time and abstain from eating in others. The limits can be set on a daily basis, weekly basis, or even change between the two.

Here Are Some Ways People Practice IF:

This method consists of fasting for 16 hours out of a 24-hour period and then eating during an 8-hour window. You have several options in terms of how many meals you can have over this period, and you can adjust the time as per your convenience; however, the longer you abstain from eating, the more potential advantages tend to become more pronounced. This plan typically works well for beginners. Begin with a shorter shifts of 12 hours or less, then increase your hours as you become more accustomed to the work.

  • Example: Stop eating after you eat dinner (6 pm) and do not eat again until lunch (12 pm) the next day.

The 5:2 approach: This style of Intermittent Fasting (IF) is labeled with numbers that relate to the number of days. For five of the days each week, have regular meals and consume nothing on the two other days. These 2 days can be divided over the course of the week in order to make it simpler.

  • Example: Eat normally Monday, Wednesday, and Friday and fast on Tuesday and Thursday.

This means abstaining from food for a period of time every other day while regularly eating on the days in between.

  • Example: Eat during a time-restricted window on Monday, eat regularly (do not fast) on Tuesday.

Energy Balance and Thyroid Functioning

No matter the circumstances, your body’s metabolism is in constant operation. The thyroid gland located in the throat is responsible for controlling the rate of metabolism and maintaining an even balance of energy. The thyroid gland takes in iodine from certain foods and joins it with tyrosine, an amino acid, to form thyroid hormones, which incorporate thyroxine (T4) and triiodothyronine (T3). The compounds originating in the brain are circulated through the body via the bloodstream, and they have an effect on things like body temperature, required calories, heart rate, and metabolism.

Hypothyroidism is the term used to describe a medical issue involving decreased activity of the thyroid gland. Signs of the condition include tiredness, weight gain, lower mental capacities, inability to tolerate cold, body heat that is lower than usual, hurt in the joints, puffiness in the face, retention of water, decrease in hair, skin that is dry, elevations in cholesterol levels, a heartbeat that is slower while resting, and sadness.

Having a thyroid issue can be quite unpleasant as it makes it difficult to shed pounds, it leaves you drained and weary, it can even lead to a low mood and having a continuous feeling of chilliness. This is a sign of this partial metabolic pause or sleep mode since the body views energy as lacking.

The HPT axis is able to respond to changes in the environment and to nutrition by altering thyroid hormones and metabolism. Going without food and cutting back on calories can lessen thyroid hormone production, which can decrease the amount of energy the body expends. But how does intermittent fasting affect this?

Does Fasting Lower Thyroid Functioning

It has been demonstrated that abstaining from eating for three days reduces serum T3 levels by 30% and thyroid-stimulating hormone by 70% in healthy males. It is believed that this is a result of decreased levels of leptin, the hormone that induces a feeling of fullness. It makes sense that if you have not had any food for an extended period of time, you will be famished, and the decreased level of leptin will result in lessening your exercise level. This is a response to a shortage of food that helps secure energy. A decreased metabolic rate will also help to safeguard against any wasting of muscle by reducing the number of calories burned.

A 4-day fast lowers T3 and raises thyroid-stimulating hormone. Men saw a greater drop than women did. Additionally, T3 and reverse T3 both go back to their original amounts prior to fasting when refeeding and going back to consuming an assortment of foods.

Nevertheless, daily time-limited eating is distinct from prolonged fasting. Intermittent fasting over a briefer period of time doesn’t cause as much stress and doesn’t interrupt thyroid functioning as much.

Research on abstaining from eating and drinking during Ramadan has revealed it does not have a large influence on the thyroids and any deviations are still in an acceptable range. Those struggling with hypothyroidism do not have to make any modifications to their regimen and they are able to partake in fasting without putting their health at risk. In some studies examining women, levels of T3 and T4 hormones have lowered, however this has not been confirmed by other research. It is speculated that the decrease is due to changes in the way proteins link with one another, considering that the free thyroid levels remain the same.

Intermittent Fasting and Hypothyroidism

It is important to think about a few elements before deciding if this form of nutrition is suitable for you. In looking at the research, here are the main takeaways for Hypothyroidism and intermittent fasting:

Intermittent Fasting May Help with Absorption of Your Thyroid Medication

Can taking synthetic thyroid hormones such as Synthroid, levothyroxine, armour, etc., provide any advantages if you fast? When taken without food, research has shown that levothyroxine is more effective and is absorbed more easily than when taken with a meal. It is advised that you take your thyroid medication first thing in the morning when you have not eaten anything. The various components that can have an effect on your thyroid medication intake can be many, but one of the most relevant ones is what you eat, as this will have an extreme impact on how well you are able to process and take advantage of the drug.

Intermittent Fasting May Aid in Weight Loss, Even with Low Thyroid

Another approach to curbing the amount of calories that you consume is to practice intermittent fasting. Generally speaking, if a person is healthy then their weight will decrease when their total calorie intake is diminished.

The majority of Intermittent Fasting investigations have revealed some level of weight reduction, ranging anywhere from 2.5 to 9.9 percent. A lot of research has been done on intermittent fasting, however, the way that it has been structured, the length of time it has been studied and the characteristics of participants have varied widely. It is essential to take into account the fluctuations that hypothyroidism can cause.

Studies demonstrate that with intermittent fasting and calorie reduction for people with hypothyroidism, body weight will decrease notably over a 6 month period. Insulin sensitivity also became lower, and concentrations of free thyroxin and thyroid-stimulating hormone stayed the same. The researchers found that both alternate day fasting and reducing calorie intake result in similar amounts of weight loss, and there was no effect on thyroid hormone levels.

Studies have found that alternations in body mass and shape may be brought about by intermittent fasting.

  • Fasting Lowers Inflammation – Thyroiditis refers to inflammation of the thyroid gland. Inflammation also promotes hypothyroidism by blocking T4 conversion and inactivating thyroid hormones.
  • Fasting Lowers Blood Sugar – One study compared levels of T3 between fasting subjects and those with impaired glucose tolerance. Those who were fasting had higher T3. Researchers thought it was caused by impaired fasting glucose.
  • Fasting Helps with Autoimmune Conditions – Autoimmune conditions can cause Hashimotto’s disease, which damages the thyroid. In some studies, fasting helps to lower flare-ups of multiple sclerosis. It works by lowering inflammation and improving the immune system functioning. Fasting also helps with rheumatoid arthritis by reducing inflammation and pain.

How to Avoid Hypothyroidism From Fasting

In animal trials, administering leptin and returning leptin levels back to their pre-fasting value can stop hypothyroidism which is caused by fasting. Chan et al noticed that T3 decreased by 30% after the 72-hour fast. In mice, going without food for 48 hours causes the activity of D3 in the liver to increase, reducing the amount of T3 that’s present in the liver. However, the effects of that are reversed when leptin is administered.

It’s also important to nourish and refeed properly. Cutting back on calories on its own can reduce thyroid activity, especially when accompanied by fasting. A research study from 1980 observed that obese test subjects had lower-than-normal T3 levels even after a fast for 10 days, followed by 5 days of eating 1500 calories a day. It might be beneficial to continue eating at the same amount as before the fast to give the thyroid a chance to nuture and lift itself out of energy deficiency.

It has been demonstrated that dietary refeeding using a primary source of carbohydrates can undo the impacts of fasting on levels of serum T3 and rT3, even when the food consumed is lower in calories. Carbohydrates are the primary energy source for thyroid hormones and leptin. Insulin is necessary to increase metabolic rate by converting T4 into T3. The importance of these things is undeniable in terms of managing the functioning of the thyroid and increasing thyroid hormones.

Iodine is a critical nutrient for sustaining good thyroid health, as it is necessary for the production of thyroid hormones. Selenium and zinc are also essential for this. Seafood, sea vegetables, meat, nuts, and organ meats are all possible sources of them.

Should You Fast With Hypothyroidism

If you experience the issues associated with a low functioning thyroid, it is prudent to take a break from lengthy fasting to provide your body a chance to recuperate. You wouldn’t want to do multiple 2-3 day fasts as that would damage your metabolism, so it’s better to stick to daily time-restricted eating and consume all your meals within a 10-12 hour period. Fasts of up to 16 hours duration are acceptable as long as you don’t undertake strenuous exercise or take stimulants during this period.

Going without food for two days has been shown to increase metabolic rate by 3-14% due to the release of epinephrine. Fasting for an entire day will vastly enhance growth hormone production by 1300-2000%, which is greatly beneficial for burning fat, preserving muscle, and supporting cellular rejuvenation. These quickly extended periods of fasting that go from 40-72 hours could be advantageous when it comes to targetting fat and creating a positive strain that quickens up the metabolism.

Extended fasts that last for 3-5 days will cause a decrease in metabolism and energy production. Fasting for 5-7 days might lead to major weight loss, but it would create much more difficulty in life once it is over. It’s likely that some of the lost weight will be regained, but your metabolism will not return to normal for an extended period afterward. In my opinion, two or three day fasts are ample. Going without food for 16 hours out of the day with an 8-hour window for eating or eating just one meal a day (OMAD) is a safe option for intermittent fasting.

How to Determine If Intermittent Fasting Is Right for You?

IF is an alternate way to eat that provides you with more leniency when selecting meals, and some people value this liberty. IF is not for everyone though! It is important to consult with your doctor to determine if this is an appropriate choice for you.

Furthermore, abstaining from food is not recommended for individuals below the age of 18, pregnant women, individuals with a history of eating disorders, or people suffering from diabetes or glucose imbalances. Have a conversation with your physician if you have diabetes and are pondering fasting.


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