Labs I Run for Resistant Weight Loss That Are Not in Routine Blood Work

If you feel like you’re doing all the right things and your weight is not changing, that is a sign! You’re eating well. Moving your body. Trying to manage stress. Getting your steps in. Maybe even tracking your food. And usually your body would be responding.

And when it doesn’t, most people assume they need to eat less, exercise harder, or be more disciplined. But resistant weight loss is often your body asking for a deeper look.

As a naturopathic doctor, this is one of the biggest reasons I often look beyond routine blood work. Routine labs are excellent for screening for disease, major abnormalities, and obvious red flags. But they are not always designed to answer the question, why am I having this symptom? And that is a very different question.

When I review labs, I’m not only asking whether something is technically “in range” or looking only for a disease state. I’m looking at what may be optimal, what trends are developing over time, and what subtle shifts may be showing up long before usual blood markers are officially flagged.

So if weight loss feels unusually resistant, here are some of the markers I often investigate further, and that you can talk with your GP or naturopathic doctor about for yourself. (or work with me here!)

Fasting Insulin

One of my favourite markers for resistant weight loss.

Your HbA1c and fasting blood sugar may look completely normal, but your body may be working very hard behind the scenes to keep it there. Elevated fasting insulin can be an early sign of insulin resistance, long before glucose starts looking abnormal.

When insulin stays elevated, even in a fasted state, fat loss can be incredibly difficult because your body is in storage mode. Cravings can feel stronger, energy can crash, and your body may feel like it is holding on no matter how “healthy” you’re being.

A Full Thyroid Panel

A basic thyroid screen often only includes TSH.

That can be helpful, but it doesn’t tells the full story, because TSH is the very last marker to change in a larger cascade of thyroid hormones and even thyroid antibodies.

I often want to look deeper at free T4, free T3, thyroid antibodies, and sometimes reverse T3 depending on the person. This helps us understand not just whether your thyroid is being signaled properly, but whether your body is actually producing, converting, and using thyroid hormones effectively and if your thyroid is in the early phase of autoimmune attack.

Sex Hormones

Hormones like estrogen, progesterone, testosterone, and sometimes DHEA, prolactin, FSH, LH can play a huge role in metabolism, body composition, cravings, energy, muscle building, and how your body holds on to fat.

This becomes especially important during perimenopause, menopause, after pregnancy, with irregular cycles, PCOS, or if you simply feel like your body composition has changed and nothing that used to work works anymore.

Hormones shift. And your strategy may need to shift with them.

Cortisol

Cortisol is your stress hormone, and chronic stress can absolutely affect weight loss.

If your nervous system is constantly in go mode, if you’re under eating, over exercising, sleeping poorly, emotionally overwhelmed, or constantly rushing, your body may not feel safe enough to prioritize fat loss.

Cortisol can impact blood sugar, cravings, appetite regulation, sleep quality, inflammation, and how your body processed fat loss.

Cortisol high or low can be seen in resistant weight loss and should always be addressed to support all other hormonal changes.

CRP

CRP, or C-reactive protein, gives us insight into inflammation in the body. This is a very general marker, but elevation can lead us to require further investigation.

Inflammation doesn’t automatically tell us why something is happening, but it can tell us that your body may be under stress, and this causes it to hold on to weight.

That stress may be coming from poor sleep, chronic stress, blood sugar dysregulation, gut issues, immune activation, recovery problems, or something else entirely.

When inflammation is elevated, the body often doesn’t function as efficiently, and weight loss can feel harder than it should.

Weight Loss Resistance Is Information

If your body isn’t responding the way you expect, that doesn’t automatically mean you need to eat less or work harder.

Sometimes it means your body is asking you to look deeper.

This is why I often recommend working with a naturopathic doctor, especially one who focuses on lifestyle medicine and metabolic health. We often look at these numbers differently than the listed lab range suggests, not just whether something is normal, but whether it’s optimal for you.

And if you want to learn how to work with your body, your brain, and your physiology instead of constantly fighting against them, check out MelloWell for well rounded healthy recipes and clinical hypnosis to help you stick to your healthy habits!