How Much Weight Does Hashimoto’s Make You Gain?

How much weight will you gain if you have Hashimoto’s?

The short answer: 

On average around 5-15 pounds. 

The longer answer: 

It could cause as much as 50 pounds or more, depending on specific risk factors.

Don’t let this bring you down, though, because it’s absolutely possible to maintain a normal weight even if you have Hashimoto’s. 

Whether or not you gain weight, and how much, depends on these factors: 

#1. Your Diet

Hands down the most important factor for determining how much weight you will gain with Hashimoto’s is your diet. 

This not only includes the amount of food that you eat but also the quality of food that you eat. 

If you think you’re going to waltz around eating the Standard American Diet without any consequences, think again. 

As someone with Hashimoto’s, you are going to be more sensitive to your food choices (1) compared to someone without a thyroid problem. 

If you want to gain a lot of weight, do this:

• Eat a lot of ultra-processed foods
• Eat plenty of refined sugars and carbohydrates
• Drink sugar-sweetened beverages
• Drink alcohol
• Restrict your calories when you try to lose weight
• Don’t eat enough protein
• Avoid all carbohydrates, including fruit
• Overeat at every meal

Doing this will all but guarantee that your weight will skyrocket with your diagnosis of Hashimoto’s. 

If you want your diet to help you lose weight or maintain your weight then do this instead: 

• Eat only real, whole foods – this should comprise at least 80-90% of your diet
• Eat 100 grams of protein each day
• Eat at least 100 grams of whole-food carbohydrates each day
• Eat plenty of fruits and vegetables
• Eat natural fermented foods
• Eat fish at least twice per week
• Don’t overeat, but make sure you aren’t hungry all day either

Eating the right foods will prevent the dreaded weight gain that most patients with Hashimoto’s experience and should even help you lose some weight in the process. 

If you do not pay attention to your diet, you can expect to gain much more weight than the 10-15 pounds I mentioned earlier. 

Instead, it might be as high as 50 or more depending on how aggressively you follow the guidelines mentioned. 

Yes, It will take some discipline and hard work to get your diet under control, but it will pay off in the long run. 

Some people have been able to put their entire disease into remission with just dietary changes alone. 

#2. The Severity of Your Disease

How much weight you gain is also a product of the severity of your disease. 

The worse your disease state, the more weight you will gain. It’s that simple. 

This is because your thyroid regulates your metabolism (2). 

But how do you know how bad your Hashimoto’s is?

This one is tricky, but there are some things that can help you make an educated guess. 

One is your lab tests at diagnosis. 

We know from studies that people who have higher a TSH at the time of their diagnosis have a worse prognosis. 

Because the TSH is a reflection of your thyroid gland’s function, a high TSH indicates more thyroid gland damage and less thyroid hormone production. 

This also applies to your thyroid antibody levels (3). 

Higher thyroid antibodies are associated with more thyroid gland inflammation and more thyroid gland damage. 

This is one reason why it’s so critical to get those antibodies under control as quickly as possible. 

It’s also why patients with seronegative Hashimoto’s experience very little weight gain because their thyroid antibodies are negative at the time of diagnosis. 

Another is your dose of thyroid medication. 

If you need higher-than-average doses of thyroid medication to get your symptoms under control then you can infer that you have worse thyroid function. 

The average dose of levothyroxine required for most patients with Hashimoto’s is around 100 mcg per day. 

If you take less than that, it’s a good sign. 

If you take more, it’s a sign you probably have more damage than the average person. 

The good news about disease severity is that it can be 100% managed.

Meaning, even if you have a rip-roaring case of Hashimoto’s, you aren’t destined to gain a ton of weight provided you are on the right treatment. 

Which just so happens to be #3 on the list: 

#3. Your Treatment (In other words, Which Thyroid Medication You’re taking)

The whole reason you are taking thyroid medication if you have Hashimoto’s is to replace the lost thyroid hormone that your gland is unable to create on its own. 

In theory, it sounds really easy to do. Take thyroid medication until your TSH is normal and you’re good to go. 

You won’t gain any weight or have any symptoms. 

But in the real world, it’s a lot more complicated. 

The reason is that your body uses more than just 1 thyroid hormone. 

But when doctors prescribe thyroid medication, they typically only provide you with one type and it happens to be the weakest. 

To complicate things even further, there’s evidence to suggest that some thyroid medications may even lead to weight gain (4). 

Levothyroxine is one of those, but I’ve seen it happen with others as well. 

If weight management is your goal then you’ll want to make sure you are taking a combination of thyroid hormones including T2 and T3. 

Studies have shown that thyroid patients who switch from levothyroxine to T3, even while maintaining similar TSH levels, see a drop in their weight without any changes to their diet or exercise (5). 

This highlights just how powerful T3 is at regulating metabolism. 

By the way, similar findings have been seen with T2 as well (6). 

In a perfect world, you’d want to find a combination of T4, T3, and T2. 

For managing your weight, that might look like: 

• 70-80 mcg of levothyroxine
• 10-20 mcg of liothyronine
• And 100-200 mcg of 3,5 diiodo-l-thyronine

If you prefer to use NDT like Armour Thyroid then that would look like this:

• 1-2 grains of Armour Thyroid (or pick your favorite NDT)
• And 100-200 mcg of 3,5 diiodo-l-thyronine

Levothyroxine by itself can sometimes work but if you find that you’re constantly gaining weight while taking it, you may want to consider other options. 

#4. Your Genetics

Genetics will obviously play a role here as well and not just because of their impact on your risk of autoimmune disease. 

Instead of this what I’m referring to is your body’s innate ability to burn fat and burn muscle. 

We know that some people and some body types are just more prone to gaining weight compared to others. 

People who are more prone to weight gain are called endomorphs (7). 

These people tend to have different hormone patterns, a naturally bigger appetite, different enzyme functions, and different movement patterns which all contribute to easy weight gain. 

If you “win” the genetic lottery and you are someone who is an endomorph who also happens to have Hashimoto’s, then it’s going to be really easy for you to gain weight. 

Having this somatotype doesn’t doom you to weight gain forever, it just means you’re going to have to be vigilant about your diet and activity level. 

It’s hard to put an exact number on your genetics, but getting dealt a bad hand genetically speaking is enough to bump your Hashimoto’s weight gain to 30 pounds or more. 

The silver lining in this is that endomorphs gain muscle easier than other somatotypes which is a boon to your metabolism. 

You just have to figure out how to manage the extra fat that comes along with it. 

#5. How Much Water You Retain

It often surprises patients with Hashimoto’s to know that much of the weight they gain is not from fat but from water (8). 

In many cases, this fluid retention can account for as much as an extra 5-10 pounds of weight on the scale. 

Sometimes it even goes unnoticed by hiding in big tissues like your legs. 

But other times, it’s obviously because you can see it around your eyes and face. 

It can be hard to differentiate between water and fat, but you can often find the difference by looking at your weight on the scale. 

The scale is a pretty terrible way to assess your weight as a thyroid patient, but it does come in handy here. 

If you check your weight daily and you see swings of multiple pounds day to day, that’s a flashing indicator that fluid retention is causing your problem. 

If you see a more gradual increase in your weight week after week, that’s probably a sign you’re gaining fat instead. 

The good news is that it’s much easier to get rid of extra fluid than it is fat. 

And you can often see an almost immediate drop in water weight once you get on the right type of thyroid medication. 

#6. Your Physical Activity & How Much You Exercise

It should come as no surprise that thyroid patients who are more active will gain less weight than those who aren’t. 

And it’s not necessarily because of the extra caloric burn, though that is certainly beneficial. 

More of it has to do with how exercise impacts your thyroid (9) as well as your other hormones like insulin. 

Combining a sedentary lifestyle with hypothyroidism is a recipe for a lot, and I mean a lot, of weight gain. 

But when you exercise, you not only improve your metabolism by increasing your thyroid, you also help your body become more sensitive to insulin (10). 

This means you will be better able to use fat as an energy source. 

The symptom of fatigue is something that keeps a lot of thyroid patients from exercising, but the thing is, exercise and movement can actually give you more energy. 

So it’s less about killing yourself with hours and hours of cardio and more about just being active and pushing your body to whatever you are capable of. 

Putting It All Together

When you put all of this together, here’s where we end up:

The average patient with Hashimoto’s will gain around 5-15 pounds after their diagnosis and an extra 2-5 pounds per year if they do nothing. 

Probably about half of this will be due to water weight and constipation. 

But if you change your lifestyle, exercise regularly, eat whole foods, and optimize your thyroid, you can completely maintain a lean and healthy body. 

And this should be the goal of every patient with Hashimoto’s. 

One of the first things you should do is change your diet. 

And if you want to see the best diets for Hashimoto’s then be sure to check out this article next.