By symptom
Weight loss resistance.
You eat well, you train, the scale doesn’t move. Something deeper is in the way.
What’s actually going on
How I think about this.
Weight loss resistance is one of the most frustrating presentations in adult medicine. The patient is doing the work, often more than their friends who are losing weight effortlessly, and nothing is changing. The conventional answer (“eat less, move more”) is both insulting and wrong here, because the calories-in-calories-out model assumes the body is running normally. In this presentation, it isn’t.
The drivers I see most are insulin resistance (your cells stop responding to insulin, fat storage stays on while the rest of metabolism slows), thyroid drift (subclinical hypothyroid will absolutely prevent weight loss), the cortisol-weight loop (chronic stress signals the body to hold fat around the middle), inadequate protein (the muscle you lose during a deficit drags resting metabolic rate down), sleep loss (one week of bad sleep is enough to register in insulin sensitivity and hunger hormones), and gut dysbiosis (the bacterial population shifts in ways that change how many calories you extract from the same food).
For women specifically, perimenopause changes the metabolic calculus, and the strategies that worked at 30 do not work at 45 without adjustment.
Before anything else
When weight loss resistance needs medical evaluation.
Everything further down this page is about physiology that can contribute to this symptom. None of it replaces a conventional diagnosis, and some presentations need to be seen rather than measured. Start here.
See a physician promptly, within days
- Rapid weight gain with swelling of the legs or face, or breathlessness
- Progressive weight gain accompanied by several features that are more suggestive of cortisol excess — such as wide reddish-purple stretch marks, easy bruising without clear trauma, new proximal muscle weakness, or progressive facial/upper-body changes — deserves medical evaluation rather than optimization testing alone.
- Weight change alongside disordered eating, bingeing or purging
Worth a routine medical evaluation
- Weight that has not moved despite a sustained and genuine effort
- Weight gain accompanied by persistent fatigue, cold intolerance, constipation, or other symptoms that could reflect a common endocrine disorder.
- Weight change that began after starting or changing a medication known to affect weight or metabolism.
- Weight gain alongside irregular periods, acne or excess hair growth
- Persistent unexplained weight change without prior evaluation for common metabolic or endocrine contributors.
Weight that will not move despite real effort, with none of the above, is a reasonable situation in which to measure the metabolic system rather than to try harder at the same thing.
This list covers the presentations that most often need conventional assessment. It is not exhaustive, and it does not replace clinical judgement. If something feels wrong and is not on it, that is still a reason to be seen.
Systems that can contribute
Where weight loss resistance can come from.
Each of these can be part of the picture. None of them is the answer on its own, and finding something here does not establish that it is the reason you feel the way you do.
Insulin regulation
Insulin resistance can make fat mobilisation harder, and it commonly precedes any change in glucose.
Thyroid physiology
Hypothyroidism slows metabolic rate, though it rarely accounts for large amounts of weight on its own.
Sleep and circadian biology
Sleep restriction measurably changes appetite hormones and food choice, and is one of the more modifiable contributors.
Stress-hormone physiology
Sustained cortisol elevation affects fat distribution and appetite.
Energy intake and expenditure
Under-reporting of intake is extremely common and not a moral failing; it is a well-documented measurement problem that affects almost everyone.
Medication effects
Several psychiatric, diabetes and steroid medications cause weight gain, and this is often not mentioned when they are started.
Sex hormones
The menopausal transition shifts fat distribution independent of total weight.
The physician’s lens
How I read this in practice.
I read weight loss resistance across the full metabolic and hormonal system. Fasting insulin alongside HbA1c, because insulin moves first by years. The full thyroid panel including reverse T3. Cortisol across the day. Sex hormones with binding proteins, especially in perimenopause. The metabolomic panel for the upstream nutrient and mitochondrial story. A DEXA scan to read what is actually changing in body composition while the scale stays flat. Often muscle loss is hidden under the same number.
The systems behind it
Where this symptom comes from.
Most cases touch more than one. Open each area to read the biology underneath.
Biological pillars
Pillar
Mitochondria & Cellular Energy.
Mitochondria produce most of the energy every other function depends on. Aspects of that function can be assessed, and much of it responds to how you live.
Read this pillarPillar
Chronobiology.
Every hormone, immune function, and metabolic process runs on a circadian schedule. The disruption is measurable, and the consequences are systemic.
Read this pillarPillar
Gut-Immune Health.
The gut microbiome interacts extensively with immune, metabolic, and gastrointestinal physiology. Read the ecosystem as one system.
Read this pillar
What measurement settles
What testing can and cannot tell you here.
Testing can help identify
- Measure fasting insulin and glucose together, which is more informative than either alone
- Identify thyroid dysfunction and the metabolic pattern of PCOS
Testing cannot by itself establish
- Explain why weight is not moving, which is usually multifactorial and includes intake, sleep and activity
- Measure your metabolic rate, which requires indirect calorimetry
- Determine whether a weight-management medication is appropriate for you
What may help clarify it
The data that explains it.
Weight loss resistance needs the metabolic and hormonal systems read together. Insulin and HbA1c, the full thyroid axis, sex hormones with binding proteins, the inflammation markers. The DEXA scan tells me whether the scale’s stability hides muscle loss the patient cannot feel.
While you wait
Moves worth making before testing.
These are the levers I’d pull while we set up the workup. Most of them produce real signal inside two weeks.
- Eat 30 grams of protein at breakfast. Protein at the front of the day stabilizes everything that follows.
- Lift heavy two to three times a week. Muscle is the most expensive metabolic tissue you can build.
- Anchor sleep to a fixed wake time. Insulin sensitivity collapses faster from sleep loss than from almost any dietary mistake.
- Stop snacking between meals. The body needs digestive rest hours to read its own fuel state.
If two weeks of the basics doesn’t move the needle, that is the kind of presentation a call with me exists for. Your biology is telling you something the lifestyle layer cannot fix on its own.
Your next step
Measure it, then decide.
There is a coherent measurement pathway here. What a panel does not include is someone reading it against your history, and that reading is where care with me begins.
What to read next
Go one level deeper.
- How I think
- The framework: how a symptom, a result and a history are read together, and why a reference range is not the same as a person’s range.
- The systems
- Mitochondria & Cellular Energy · Chronobiology · Gut-Immune Health
- Terms used here
- DEXA scan · Dysbiosis · Fasting insulin · HbA1c · Insulin resistance · Mitochondria
Essays on this
Essay
A fasting insulin of 12: what it can, and cannot, tell you.
A fasting insulin of 12 may fall inside a laboratory's reference interval beside a normal glucose. It can add context that glucose and A1c do not give on their own, but it is a proxy, not a diagnosis: there is no universal cut-off, laboratories do not agree, and it is read beside standard testing and repeated before it means anything.
Read thisEssay
An ALT of 45: the most common liver disease in the world, dismissed.
An ALT of 45 gets waved off as mildly elevated or not flagged at all. In most people it is fat in the liver driven by the same insulin resistance showing up elsewhere on the panel, and a free calculation from numbers you already have tells you whether to worry.
Read thisEssay
The gut has a circadian rhythm. Why meal timing matters.
Your gut runs on a circadian rhythm. The same food eaten at 2 p.m. produces a different metabolic response than the same food eaten at 10 p.m. The implications for weight, sleep, and metabolic health are significant.
Read this
Browse other symptoms
Something else on your mind?
Fatigue and low energy
When the tank stays low no matter how much you sleep.
Brain fog
The lights are on but the signal feels weak.
Poor sleep
Either you can’t fall asleep, or you can’t stay asleep.
Perimenopause
The years when the body’s hormonal rhythm changes, before the period stops.
Low libido
Desire that used to be reliable is gone or muted. Both sexes, both directions.
Hair loss
Thinning, shedding, or texture changes that didn’t used to happen.
Erectile dysfunction
ED is the canary. The body is telling you something about vascular and hormonal health.
High cholesterol concern
Your last lab flagged it. You want a second opinion before you take a statin.
High blood pressure concern
The reading came back elevated. You want the full picture before you start a prescription.
Food cravings
Cravings are biology pulling for what it needs, disguised as whatever is easiest to grab.
The Precision Health Report
The science of optimizing your biology, sourced and translated, with no hype. A new issue by email every Friday.
Get the Report by email
Start here
Want me to read your data?
You start by applying. I read every application myself and follow up with you after review. You tell me what is going on. I tell you how I would approach it. You decide if I am the right physician for you.