How Your Diet Can Ruin Your Metabolism and Cause Weight Gain (+ How You Can Fix It)

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Many are familiar with the struggles of losing weight. All too often we experience the temporary elation of weight loss followed by an almost immediate return of the pounds we worked so hard to remove.

Another common experience you may be painfully familiar with is simply being unable to lose weight no matter how many calories you cut or how much exercise you do on a weekly basis. These situations are incredibly frustrating and share a common weight lose inhibitor; low metabolism.

Our metabolism is responsible for burning calories and giving us the energy we need to get through the day, which has powerful influence over our weight. Unfortunately, many of us have unwittingly done significant damage to our metabolisms by following diet trends pushed by our society and in some cases our doctors. 

Severely reducing your caloric intake, yo-yo dieting, or chronically dieting all have a major negative impact on your metabolism. Inhibited metabolic function makes it incredibly difficult to maintain a healthy weight let alone lose weight. There are a few important factors involved in metabolic function that take a big hit when we go on crash diets or aggressively reduce our calorie intake. But before discussing that, we need to take a look at the thyroid.

The Thyroid and The Metabolism

The thyroid influences almost every bodily function but has particular impact on the metabolism. There are three major components that must be brought up whenever we talk about thyroid function and chronic dieting; T4 or the storage form of thyroid hormone, T3 also known as the active form of thyroid hormone, and the enzyme known as Deiodinase type 1 or D1 for short.

When working properly, the thyroid produces ample amounts of T4, which then patiently waits until it is converted into T3. T3 is the active form of thyroid hormone and regulates metabolic function. Higher levels of T3 increases your metabolism while lowered levels reduce metabolic ability. Without adequate levels of T4 being produced or enough of it being converted to T3, your metabolism suffers. 

In a study presented in the American Journal of Physiology, Endocrinology, and Metabolism it was found that after only 25 days of restrictive dieting, various areas of thyroid function were negatively impacted; primarily involving T3 levels. The patients presented a 50 percent reduction in T3 levels meaning that their metabolism was severely crippled simply due to overly aggressive dieting. Patients also experienced a significant reduction of T4 to T3 conversion. Reduced levels of T3 caused by poor T4 conversion can result in lethargy, fatigue, and an inability to lose weight. 

The reason that T4 to T3 conversion suffers so greatly from chronic dieting is because of its impact on the previously mentioned D1. This enzyme is responsible for converting T4 into T3 and is negatively impacted by physiological and emotional stress as well as dieting. The combination of caloric restriction (physiological stress) and anxiety associated with new diet plans (emotional stress) can do a number on D1’s ability to convert T4 to T3. Women are particularly prone to experiencing metabolic dysfunction due to stress because they have naturally lower levels of D1. That being said, chronic diets can seriously damage anyone’s metabolism for extended periods of time regardless of their gender. 

The Problem with Chronic Dieting

A study presented in Metabolism found that those who had lost even moderate amounts of weight have lower metabolisms than those who maintained the same weight for over a year. This means that even though two individuals weighed the same, the one who had lost weight to reach that level had a metabolism that was 25 percent less functional than the person who had not lost or gained notable weight in the previous year. Worse still, the weight loss patient’s metabolism remained reduced for multiple years making it more difficult to maintain that weight. 

Imagine losing 25 percent of your metabolism. That means you would have to reduce your intake by roughly 500 to 600 calories every day just to maintain your current weight level! The tragic irony of chronic dieting is that the people who utilize them are usually trying their hardest to lose weight when in reality they are doing significant long-term damage to their metabolism and making their weight goals significantly more challenging. However, this should not dissuade you from achieving greater health.

Restoring Metabolic Function

With the many negative and long-lasting effects associated with chronic dieting, it may seem impossible to save your metabolism. However, there are many ways you can support your metabolism and coax it back to its previously healthy level.

The following tips can help you restore metabolic function resulting in improved energy levels, better focus, and ease the difficulty of achieving your weight loss goals.

Breakfast of Champions

It may seem counterproductive but eating is a great way to support weight loss. By beginning your day with a healthy breakfast (something light that won’t weigh you down for the rest of the day) keeps your body from jumping into starvation mode. A small meal containing fruit and a little protein is enough to get the metabolism up and running.

Not eating for an extended period of time tells the body it needs to hang on to calories and slows down the metabolism meaning that you become less effective at burning fat and ultimately hold on to excess calories and weight.

Consider Caffeine

Caffeine, whether it be found in coffee or tea, may be beneficial for your metabolism. Drinking a small amount of caffeine in the morning can help boost your metabolism for the rest of the day. It is of course best to drink any caffeinated beverage in moderation as too much can raise heart rate and cause one to feel jittery and unfocused. 

Reduce Stress

Stress is a notoriously common cause of reduced metabolic function. Unfortunately, we live in a world where almost everyone experiences a notable amount of stress on a daily basis. Removing unnecessary stressors from your life can not only improve mental wellness but help restore your metabolism. Resolving common stressors such as toxic relationships, overwork, and lack of sleep can help restore metabolic function. Pursuing stress relieving activities such as massage, yoga, or sipping herbal tea can also help reduce your stress levels.

Get more stress-reducing tips here.

Improving Your Metabolism and Overall Health

Even if you have fallen into the trap of chronic dieting and are now suffering the consequences of a reduced metabolism there is still hope! By taking care of your body and pursuing metabolic boosting practices such as those listed above you can revitalize your metabolism and increase your ability to safely and effectively reach your target weight.

At Holtorf Medical Group, our physicians are trained to provide you with cutting-edge testing and innovative treatments to find the answers you deserve and a treatment plan that is personalized to your specific condition. If you’re experiencing unexplained weight gain or weight retention and believe your thyroid may be to blame, give us a call at 877-508-1177 to see how we can help you!


1. Araujo RL et al. “Tissue-specific deiodinase regulation during food restriction and low replacement dose of leptin in rats.” Am J Physiol Endocrinol Metab. 2009 May;296(5):E1157-63.
2. Leibel RL, Hirsch J. “Diminished energy requirements in reduced-obese patients.” Metabolism. 1984 Feb;33(2):164-70.
3. Fontana L, Klein S, Holloszy JO, Premachandra BN. “Effect of long-term calorie restriction with adequate protein and micronutrients on thyroid hormones.” J Clin Endocrinol Metab. 2006 Aug;91(8):3232-5.
4. Kent Holtorf. “Peripheral Thyroid Hormone Conversion and Its Impact on TSH and Metabolic Activity.” DOI: 10.14200/jrm.2014.3.0103.
5. Agnihothri, Ritesh V et al. “Moderate weight loss is sufficient to affect thyroid hormone homeostasis and inhibit its peripheral conversion.” Thyroid: official journal of the American Thyroid Association vol. 24,1 (2014): 19-26.

About Holtorf Medical Group

The Holtorf Medical Group specializes in optimizing quality of life and being medical detectives to uncover the underlying cause of symptoms, rather than just prescribing medications to cover-up the symptoms. We are experts in natural, prescription bioidentical hormone replacement and optimization, complex endocrine dysfunction, fibromyalgia, chronic fatigue syndrome and Lyme disease.

We’ve dedicated our practice to providing you the best in evidenced-based, integrative medicine that’s not only safe and effective, but provides measurable results.