If you’ve been diagnosed with hypothyroidism, or underactive thyroid, there’s a good chance you may be struggling with your weight.
Hypothyroidism happens when the thyroid gland doesn’t produce enough thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). These two hormones help your metabolism convert food into energy,¹ and weight gain is a common early symptom of hypothyroidism.
The good news: despite what you may have heard, a hypothyroidism diagnosis doesn’t mean you’re destined for a lifetime of weight struggles.
How hypothyroidism affects metabolism and weight
According to the American Thyroid Association, hypothyroidism can be credited for around five to 10 pounds of extra body weight.²
Again, this is partly because of the role thyroid hormones play in metabolism. When thyroid hormones are released into the bloodstream, they travel to every tissue in the body and help convert calories from food into energy. This process keeps your organs and muscles working and puts you at a comfortable body temperature.³
If your body isn’t producing enough T3 and T4, your metabolism will slow, making it harder to convert calories into energy (and making you tired in turn). Essentially this means your body isn’t burning available calories the way it should be.⁴ ⁵
There’s also evidence that underactive thyroid hormone levels contribute to insulin resistance — when cells in your muscles, fat and liver don’t respond well to the hormone insulin and can’t easily use glucose, or sugar, from your blood. This prompts your body to pump out even more insulin to help balance blood sugar, which can ultimately promote weight gain.⁶
How can you lose weight with hypothyroidism?
If you’re wondering if it’s even possible to lose weight with hypothyroidism, the answer is yes. The first step is getting diagnosed and starting on medicine if you need it.
Get medicine if you need it
If you haven’t already, the most important way to start is by getting a thyroid hormone test and discussing the results with your healthcare professional. If you have hypothyroidism, your doctor will likely prescribe the synthetic thyroid hormone levothyroxine.
The American Thyroid Association says that most people experience subtle weight loss — usually less than 10% of body weight — when they start taking levothyroxine.
It can take a while for hormones to come back into the normal range, but once they have, losing weight should be as easy (or hard) as it is for people who don’t have thyroid problems.⁸
Boosting thyroid hormones back to normal with levothyroxine can address weight gained due to slowed metabolism, but that’s not all it does.
Dr. Jillian LoPiano, MD, is a women’s health specialist and medical director at Betty’s Co. She says that taking levothyroxine should also ease other symptoms that can make you feel like you’ve gained weight, including fatigue, constipation and bloating.
So if you have unmanaged hypothyroidism and want to lose weight, treatment should offer plenty of hope. Still, that doesn’t mean weight loss will be easy.
What else can you do to lose weight with hypothyroidism?
“Weight gain is complex,” says Dr. LoPiano. Treating hypothyroidism should resolve the weight you gained with your condition, but it won’t eliminate extra weight you might be carrying for other reasons.
Instead of fixating on a number on the scale or a specific rigid diet (which are often counterproductive for long-term weight loss⁹), Dr. LoPiano suggests shifting your focus to simple, nourishing habits you can maintain for life. And don’t forget to talk to your doctor about any weight you lose (or gain!) while taking levothyroxine, as weight changes can affect dose.
Here are some doctor-approved strategies for healthy weight loss:
1. Boost your micronutrient intake.
Even if you’re not dealing with a thyroid issue, micronutrients, aka vitamins and minerals, are essential to your health.
One study found that successful “weight loss maintainers” were more likely to consume foods with greater micronutrient density than a control group of obese patients.
Specifically, they were more likely to get enough copper, magnesium, potassium, vitamin A, vitamin B6 and vitamin C.¹⁰ In addition, iodine, iron, selenium, zinc and vitamin D are all integral to healthy thyroid function.¹¹ ¹² ¹³
The easiest way to increase micronutrient intake is to shift your diet away from processed foods and towards whole, unprocessed items such as:
- Nuts and seeds
- Whole grains
- Lean proteins
- Healthy fats
2. Don’t skimp on protein.
To build muscle strength, a moderately active 150-pound person should be eating around 88 g of protein per day, divided among meals.¹⁶
According to the United States Department of Agriculture (USDA), most Americans get enough protein in their daily diet — the challenge is choosing a variety of proteins.¹⁷ The USDA suggests choosing more of these protein foods:¹⁸
- Vegetarian options such as nuts, seeds, beans, peas, lentils and soy
- Lean or low-fat beef, pork or chicken
- Seafoods high in omega-3s, such as salmon, anchovies and trout
3. Fill up on fiber.
Hypothyroidism can mean sluggish digestion, constipation and bloating. While these things don’t add actual weight, it can feel like they do.
Since fiber promotes softer, bulkier stools, adding more of it to your diet can make it easier to pass excess materials you might be holding in your digestive system. High fiber diets also promote stable blood sugar and help keep you full between meals.
The recommended daily fiber intake is 25 to 35 grams, yet the average American consumes about half that.²¹
Most whole or minimally processed foods contain fiber, but some particularly good options include:²²
- Vegetables such as kale, collard greens, broccoli and artichokes: 4.7 to 9.6 grams of fiber per cup
- Beans and legumes such as lentils, navy beans, green peas and adzuki beans: 7.5 to 9.6 grams per ½ to 1 cup serving
- Root vegetables such as yams, parsnips, sweet potatoes and taro: 5.3 to 6.7 grams per cup
- Fruit such as blueberries, blackberries, raspberries and guava: 6.2 to 8.9 grams per cup
4. Scale back on simple carbs and sugars.
Eating too many refined carbohydrates and added sugars — present in foods like white bread, pasta, sugary cereals and drinks — isn’t good for your weight or your long-term health.
Because refined carbohydrates can create a blood sugar spike,²³ they may be especially bad for people with hypothyroidism, who are often less sensitive to the effects of insulin,²⁴ the hormone that brings blood sugars down to optimal range.
5. Make sure you’re eating enough food.
It might sound counterintuitive, but slashing calories isn’t a good recipe for weight loss. For example, one study found that women who reduced their food intake to 1,200 calories per day experienced greater feelings of stress and increased levels of the stress hormone cortisol²⁵ — which is known to cause extra weight and impair thyroid gland function.
Instead, fill up on healthy proteins and fiber to increase satisfaction and reduce the likelihood of overeating.
Hypothyroidism slows the metabolism and contributes to symptoms such as bloating, constipation, exercise intolerance and fatigue — which can create both real and perceived weight gain. These symptoms can be addressed by getting on the right dose of thyroid medication. Adopting simple dietary habits can also support thyroid function and help you achieve and maintain a healthy weight without deprivation. Talk to your healthcare professional about any changes to your diet and lifestyle, since they may affect your optimal dose of thyroid medication.