Despite all the information available on metabolism and how your thyroid health affects it, this common chemical process continues to baffle us with its finicky temperament. Keeping it balanced and in working order is no easy feat. How much and what type of exercise should we be doing? Are there certain foods we should avoid altogether or be eating more of? How do we know if that advice will work for our body? Especially when you consider how different we all are.

To clear things up, we tapped nutritionist and New York Times best-selling author of The Metabolism Plan, Lyn Genet-Recitas. Her new 30-day program tailors a diet and exercise plan specific to the individual, so there’s no room for error. The difference with this plan is that it doesn’t tell you what to eat or what exercises you should do. Instead, it empowers you with the tools to analyze your own lifestyle so you can make healthier choices based on your physiology. Her philosophy? “Exercise less to lose more.” Yes, you heard right. And she also tells us you can sleep your way to a healthy thyroid. Intrigued? Ahead, Recitas debunks all the metabolism myths, explains why taking care of your thyroid will boost your metabolism, lists the foods you shouldn’t be eating, and shares other key factors that are impacting metabolic function.

MYDOMAINE: What is the number one myth you’d like to debunk about metabolic health?

LYN-GENET RECITAS: There is a myth that metabolism slows as you age—that’s actually untrue, and that’s great news. What is true is that choosing foods that cause inflammation and making certain exercise choices can slow your metabolism. The Metabolism Plan helps you find the foods and exercise that work specifically for yourbody.

MD: How are the thyroid and metabolism health interlinked? How does taking care of your thyroid help your metabolism?

LR: Your thyroid is your master gland for your metabolism. In fact, every cell in your body has a receptor site for thyroid hormones. When your thyroid is sluggish, you literally slow down every process in your body from weight loss to optimal health.

MD: What is the biggest mistake people make when it comes to diet and exercise? What are most people doing wrong? why?

LR: People are following generalized advice. In research, when something works for 70% of the population, it’s considered very effective, but often you’ll fall into the 30% that it doesn’t work for. That’s why it’s so important for you to find what works exactly for your body. Eating just one reactive food can cause an inflammatory response for up to 72 hours. Exercising too intensely can cause cortisol to rise, which skews your hormones and attacks thyroid function, slowing your metabolism and negatively affecting your health.

Then we have the flip side of people who don’t exercise at all because they think they need to spend hours a day at the gym when in fact they may only need 8 to 10 minutes to boost thyroid function and optimize health and weight loss.

MD: What are the main things slowing down our metabolism and why?

LR: Inflammatory foods and over-exercise affect your thyroid (see below diagram).

MD: What are some of the physical, mental, and emotional signs your thyroid isn’t functioning properly?

LR: Physical: Weight gain, hair loss, brittle nails, headaches, constipation, bloating, lethargy, feeling cold, and dry skin.

Mental/emotional: Foggy thinking, depression, anxiety, irritability, and low sex drive.

MD: Why is our metabolism responsible for weight gain?

LR: Since the thyroid stimulates and synchronizes the metabolic and cellular functions in every tissue throughout the body, it is responsible for weight gain. You lose the most weight when you are healing, not exercising. That’s why you can lose two pounds when you are sleeping.

MD: What are the top five foods you would remove from our diet to improve thyroid and metabolism function?

LR: There is no such thing as a universally healthy or unhealthy food, however, the foods I’ve listed below are 85% (or higher) reactive, thus we do not test them in the beginning because they have such a high fail rate.

“Exercising too intensely can cause cortisol to rise, which skews your hormones and attacks thyroid function, slowing your metabolism and negatively affecting your health.”

MD: What are the key factors that are impacting thyroid function and why?

LR: Your thyroid is affected by the following, and I clearly lay this out in The Metabolism Plan along with steps you can take to keep these factors in check:

Too much stress (whether it’s a reactive response to food or too much exercise) will attack thyroid function. Everyday stressors (deadlines at work, fights with loved ones) will lower your BBT (basal body temperature) which can impact your thyroid health. (Your core temperature is a very important measurement. Too high or too low temperatures inhibit normal body function and can be a sign of hyperthyroidism.)


Less than seven hours of sleep will lower BBT. Tips for sleep issues are mentioned in TMP. Heightened stress levels will affect sleep. Removing the factors such as over-exercise and inflammatory foods provide better sleep in just days.


Stress, inflammatory foods, and over- or under-exercise will skew hormones (see below diagram).


Too much or too little can negatively impact your thyroid function.


There are some foods that can increase inflammation and weight gain: Salmon, Greek yogurt, asparagus, turkey, strawberries, roasted nuts, quinoa, spinach, and hard boiled eggs.

MD: Who is at higher risk of earlier thyroid issues?

LR: Thyroid disorders are much more common in women than men until the age of 40. In women, adequate binding of T3 (the active thyroid hormone) is dependent upon sufficient progesterone. Reactive foods and over-exercise create estrogen dominance and low progesterone. Hormonal imbalances attack thyroid function.

Men start to catch up with thyroid imbalances starting in their 40s, and by the time they are in their 60s are neck and neck with women at roughly 85% dysfunction. Low testosterone, extreme exercise, and vegetarian diets can lead to hypothyroidism. Nutritional deficiencies are also a major cause for thyroid dysfunction. Higher rates of stress also affect the thyroid in both sexes.

“If you’re gaining weight from exercise or healthy foods, that is your body saying, I love you, please stop doing this. It doesn’t work for us,” she told MyDomaine. “So in effect, your scale is your best friend. All it does is give you data and every single day your body is talking to you and this plan helps you to figure out exactly what it is saying.”

MD: You mention in your book that we can sleep our way to thyroid health, and, in fact, it actually is one of the best possible ways to support your weight—how?

LR: When you sleep less than seven hours (most people need at least seven hours), you will actually see your BBT drop (your BBT is an indicator of how metabolically active you are for the day). For every two hours of sleep that is lost we see weight loss affected by 0.2 to one pound, with 0.6 pounds weight gain as the norm.

This article originally appears in Thrive Global

Your friend in health,

Lyn-Genet Recitas


Nutritionist and NYTimes best-selling author of The Plan, The Plan Cookbook and The Metabolism Plan.

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