Everyone Starts in January. January Is the Worst Possible Month to Start.

You know exactly how this goes, because you have run it about twenty times.

Late December, you make the decision. Properly this time. The cupboards get cleared out on the 30th — the tin of chocolates goes, the leftover crackers, the bottle of something nobody drank. You buy the containers. You write the plan out.

January 2nd it starts, and the first two weeks are genuinely good. You feel it working. You tell someone.

And then somewhere in the third week of February, you are standing at the counter at nine at night eating toast. Not sitting down to eat it. Standing, in the dark kitchen, with the light off, having a second slice.

You could not tell anyone what happened.

That is the part that has bothered you for two decades. It is not that you stopped caring — you did not, you care now, you cared the whole time. It is that at some point between the second week of January and the third week of February, the entire thing got harder. Noticeably, physically harder. Same plan, same rules, same you, and it went from difficult-but-doable to something you were losing every day.

And then the specific sequence you know by heart. A week of pretending it is still on. Then the quiet abandonment, which does not have a date because you never decided it — you just noticed sometime in March that you had stopped.

The containers are still in the cupboard. The gym membership runs until December and you have used it eleven times.

So you filed it the only way it could be filed.

I always do this.

And you have carried that sentence into every attempt since, which is its own kind of tax.

I want to show you something about February that I do not think anyone has ever put in front of you. It will take about ten minutes and it covers twenty years at once.

Then I want to show you what you can do in the next six weeks — while it is still easy — so that this February is different.

Here is the assumption underneath twenty years of this, and it is so obvious that you have never once examined it.

That January is a neutral starting line.

A blank page. A clean slate. A fresh start — the whole vocabulary of the new year is built on the idea that the calendar resets and you begin from zero, with the same body you had in June, and the only variable is how much you want it.

Call it The Neutral Starting Line.

It is in the gym advertising, the meal plan launches, the January issue of every magazine, and it is in your own head every December 30th.

And notice the shape of it. If the starting line is neutral, then the only variable left in the equation is you — which means there is exactly one available explanation when things fall apart six weeks later, and it is a verdict rather than a diagnosis.

That is why twenty attempts have produced twenty pieces of evidence against your character and zero pieces of information about anything else. The frame does not permit a second explanation. It never has.

But your body in the third week of February is not your body in August.

Measurably not. Four things have shifted on a schedule — the same schedule, every year, driven by daylight rather than by anything you decide — and by late February all four are at or near their annual worst.

Your vitamin D is at its floor. Your light exposure is at its minimum. Your serotonin system is in a different configuration than it is in July. And your appetite has moved.

None of those is dramatic on its own. That is precisely why nobody notices. They arrive together, over months, so slowly that the only thing you register is that the same effort stopped producing the same result.

You have been starting the hardest thing you do all year on the single worst week of the calendar for doing it — and then explaining the outcome with a story about your character.

Two things before I show you the data.

I am writing this in mid-August, in the Northern Hemisphere. If you are somewhere else, everything here still applies — just move it. The window is the eight weeks before your daylight starts dropping, wherever you are.

And this is not the article about what happens inside a deficit. I wrote that one in February — the leptin crash, the ghrelin surge, the biological override that arrives around week six of any restriction. That mechanism is real and it stands.

This is the other half. That article explains what happens once you are in a deficit. This one explains what the calendar has already done to your starting conditions before you take a single step — and the two stack.

Three independent datasets, and they agree.

In a study of 401 patients, 25-hydroxyvitamin D3 was higher in spring and summer than in autumn and winter — 47.9 ± 22.2 versus 42.8 ± 21.8 nmol/L, P = .02 [1].

In 1,682 unselected primary care patients, summer versus winter came out at 53.4 ± 19.9 versus 41.6 ± 19.3 nmol/L, P < .0001 — and the difference held in a subgroup of 93 people tested in both seasons [2].

And in a healthy adult population, the swing was larger still: 74.97 ± 22.75 in summer against 44.13 ± 17.82 in winter, P < .001 [3].

That third study measured something the others did not, and it is the detail worth keeping. The bioavailable fraction — the portion actually free to act rather than bound up in transport proteins — fell from 13.11 to 7.45 nmol/L, and the free fraction from 29.7 to 17.3 pmol/L, both P < .001 [3].

Roughly half. Not of your total. Of the part that is available to do anything.

That decline does not happen in January. It starts when UVB drops below the threshold for skin synthesis — for most of the Northern Hemisphere, sometime in October — and your stored reserves draw down through the winter toward a floor in late winter and early spring.

Which puts the bottom of the curve almost exactly on the third week of February.

The same 401-patient study found an inverse relationship between vitamin D and TSH that held in both seasons — autumn-winter r = −0.0248, P < .00001; spring-summer r = −0.0209, P < .00001 [1]. And TSH was higher in patients who were vitamin D insufficient or deficient than in those who were sufficient, across every season [1].

Now the part most seasonal wellness articles would leave out.

The seasonal difference in TSH itself was not statistically significant. Median 1.9 mU/L in autumn-winter against 1.8 in spring-summer — P = .10 [1].

Not significant. I am putting the P value in the sentence rather than in a footnote, because a tenth is a tenth.

Two more limitations you should have. That cohort was patients referred with nonspecific tiredness, not a general population sample. And the correlation coefficients, while highly significant, are small.

So the honest version is: the relationship between vitamin D status and thyroid signaling is consistently reported and it is real. The seasonal swing in TSH is small and does not always reach significance. Anyone telling you that winter tanks your thyroid is overstating what the data shows.

This one is not soft.

Researchers used PET imaging to measure serotonin transporter binding in the brains of healthy volunteers, and grouped the scans by the season in which they were taken [4].

Binding was higher in fall and winter than in spring and summer [4].

Here is why that matters, because “transporter binding” sounds abstract. The serotonin transporter is the protein that clears serotonin back out of the synapse. More transporter means faster clearance, which means less serotonin circulating [4]. The binding potential and the amount of serotonin available move in opposite directions.

And it tracked with the astronomical data — the duration of daylight [4].

That is not a survey. It is not self-report. It is a direct measurement of a brain protein, in healthy people with no diagnosis, moving with the length of the day.

Your winter mood is not a failure of attitude. There is a different amount of serotonin available in your brain in February than there is right now, and the mechanism has been imaged.

Reduced serotonin availability is the accepted partial explanation for the winter shift toward carbohydrate — the relationship between serotonin and carbohydrate intake runs in both directions, and eating refined carbohydrate raises tryptophan availability to the brain.

But I want to grade this one honestly. The serotonin imaging is hard data. The appetite data is largely self-report, and self-report about food is the least reliable category of evidence there is.

What I can tell you is what the mechanism predicts and what almost every woman reading this recognizes: bread, pasta and sweet things become more appealing as the light drops, and evening eating in particular increases. If that describes your February, you are not imagining it. But I am not going to hand you a percentage, because the number would be softer than it looked.

I could stop here and you would close this page believing winter is metabolically worse across the board.

It is not that clean, and you should have the study that says so.

Researchers followed postmenopausal women from early autumn into winter, measuring vitamin D alongside markers of carbohydrate metabolism. Vitamin D fell as expected — P ≤ 0.0001 [5].

And insulin decreased. HOMA-IR — the insulin resistance index — decreased. Both P < 0.05 [5].

Insulin sensitivity improved going into winter, in the same women whose vitamin D was falling. The authors say outright that this was contrary to their expectations, and speculate about falling outdoor temperature raising basal metabolism, or dietary changes in the pre-Christmas period [5].

That is one study, in one population, and it does not overturn the wider literature linking vitamin D status to insulin sensitivity. But it is real, it was published, and it points the opposite way to the story I have been telling you.

So here is my actual position, with nothing rounded off.

Light exposure falls. Vitamin D falls, substantially, and the bioavailable fraction falls further. Serotonin transporter binding rises and available serotonin drops, and that one is imaged rather than surveyed. Appetite shifts toward carbohydrate, on softer evidence.

The downstream metabolic picture is genuinely mixed, and anyone who tells you otherwise has not read the whole literature.

But you do not need the metabolic picture to be settled for the practical conclusion to hold — because the practical conclusion is not about metabolism. It is about conditions. Four things that support a behavior change are at their annual best right now and their annual worst in February, and that is not in dispute in any of the studies above.

That is The Moving Baseline. You have never been starting from the same place.

And it is worth being precise about how they interact, because the compounding is the part that makes February feel the way it does.

None of the four is large. A drop in available vitamin D does not make you feel anything. A shift in serotonin transporter binding does not announce itself. Slightly more appetite for bread is not a symptom.

But look at what each one costs you in the specific context of trying to change a behavior.

Lower serotonin availability means less capacity to tolerate discomfort and delay reward — which is the entire currency a new habit is bought with. More appetite for refined carbohydrate means the discomfort you are tolerating is larger. Less daylight means the outdoor part of your routine has become an act of will rather than a pleasure. And low vitamin D status is associated with the fatigue that makes all three of the above harder.

You are not being asked to do the same thing under slightly worse conditions. You are being asked to do a harder version of it with less to spend.

That is why February feels the way it does, and it is why the same plan that felt manageable on January 4th felt impossible on February 20th without a single thing about the plan having changed.

❤️ Real Talk: Twenty Februaries, each one filed as a personal failure. That is a lot of evidence to have collected against yourself, and every piece of it was collected in the same six-week window of the year, under conditions you did not know were changing. You were not weaker in February. You were working uphill and calling it flat ground.

No studies here. Three questions about your own history.

First. Think about the last three attempts, and put a date on when each one actually ended.

Not when you formally gave up — you probably never did formally give up. The week it stopped being something you were doing and became something you had been doing.

Write the three months down.

For most people they cluster. Late February, early March, late February. Three separate attempts, three different plans, three different years — landing in the same three-week window.

That is not a coincidence about your discipline. Discipline does not have a season. The calendar does.

Second. Now think about a change you made that actually stuck.

Not a diet. Anything — a walk you started taking, a thing you cut out, a habit that just became how you do it now. Most people have at least one.

When did it start?

I would guess spring or summer, and I would guess you have never connected that to the fact that it held. The behaviors that survive in your life are disproportionately the ones you happened to install when the conditions were good — and you have credited that to the behavior being a better fit for you, rather than to the month it was born in.

Third, and this is the one worth sitting with.

Twenty years is a long time to gather evidence about yourself.

Every one of those Februaries produced the same conclusion, and the conclusion got a little heavier each time. By now it is not a thought you have — it is closer to a fact about you, held so firmly that it shows up before the attempt rather than after. You already know how this goes. You said so at the top of this article.

That is The February Verdict, and here is what I would like you to notice about it: every single piece of evidence supporting it was collected in the same six-week window of the year, under conditions you did not know were changing.

Not one of those twenty data points was gathered in August.

You have never once tested yourself under favorable conditions and then judged the result. You have tested yourself twenty times at the bottom of the curve, and drawn a conclusion about your character from it.

❤️ Real Talk: You are not looking at twenty failures. You are looking at one scheduling error, repeated twenty times, by someone following the only calendar anyone ever handed you. The evidence you have been holding against yourself was collected under conditions that guaranteed the result.

Here is the reframe that makes the rest of this article different from anything else you will read this month.

You are not fixing anything right now. Nothing is wrong. That is exactly the point — it is August, the conditions are as good as they get, and there is nothing to rescue.

You are installing something while installation is easy.

Because here is the thing nobody says about new habits: the difficulty of starting a behavior and the difficulty of maintaining one are two different numbers, and starting is far more expensive. A behavior that is already automatic in October will survive November. The identical behavior, begun in November, will not — not because you are different in November, but because you are paying the installation cost at the exact moment the conditions have turned.

That is The Runway. You have about six weeks of it. Not because I am creating urgency — because that is when the light starts to go.

Twenty to thirty minutes outdoors, within an hour of waking. Not through a window — glass blocks most of the relevant wavelengths. Outside, without sunglasses, even on an overcast day.

This is the highest-value item on this page and it costs nothing.

Why now rather than in October: because in August this is pleasant. Getting up and going outside is not an act of will in August — it is a nice thing to do. In November, in the dark and the cold, it becomes an act of will, and acts of will are precisely what you run out of.

Install it now while it is free. By the time the mornings are dark, it will be something you already do rather than something you have to make yourself do.

The practical version: attach it to something you already do daily. Coffee outside. The dog. The first ten minutes of a podcast on the doorstep. Walk to somewhere rather than deciding to go for a walk.

And the winter fallback, decided now rather than in November. There will be mornings when it is dark at your wake time and going outside is genuinely not happening. Decide today what happens on those days — the ten minutes at lunchtime instead, or the walk to the car taken deliberately rather than at speed, or a lamp on the kitchen table while you eat breakfast.

The reason to decide it in August is that a habit with a defined fallback survives a bad week, and a habit without one ends at the first bad week. That is close to the whole science of habit maintenance in one sentence, and it costs you thirty seconds to apply.

Not January. September.

Get your 25(OH)D tested before the decline, so you know what you are starting the winter with rather than finding out at the bottom. A level that is comfortable in August and a level that is comfortable in August and will still be adequate in February are two different numbers.

I have written about vitamin D forms, doses and the D3-plus-K2 pairing in full in the supplements article and I am not going to repeat any of it here. What this entry owns is the timing — that the test belongs before the decline, not after it, and that the conversation happens with someone who can see your number.

One thing worth understanding about why September and not October. Your skin stops making vitamin D when UVB drops below a threshold, which in most of the Northern Hemisphere happens somewhere in October. Everything after that point is drawdown from storage.

So the number you have in September is roughly the highest number you will have all year, and it is the one that determines how far you fall by March. Testing in February tells you where you landed. Testing in September tells you what you are working with — which is the difference between information and a postmortem.

❤️ Real Talk: Notice how much of this article is just moving things earlier. Not doing more, not trying harder, not adding anything — the same test, the same walk, the same meal, done in a month when they are cheap instead of a month when they are expensive. Twenty years of effort was never the missing ingredient. Timing was.

The 9pm toast is not random. It arrives at the specific point in the year when serotonin availability is lowest and carbohydrate is most appealing, in the specific part of the day when structure is weakest.

So build the structure now, in the season when you do not need it.

A defined evening meal, at a roughly consistent time, containing 25 to 30 grams of protein. A palm-sized piece of fish, chicken or meat. A cup of Greek yogurt with seeds. Two eggs plus half a cup of cottage cheese. Three-quarters of a cup of lentils or beans.

And a defined end to eating — a time after which the kitchen is closed. Pick one and hold it in August, when it costs you nothing, so that it is already the shape of your evenings when February arrives and starts pulling in the other direction.

The reason this one specifically is worth installing early: in August, closing the kitchen at eight is a rule you barely notice, because you are not especially hungry at nine in August. In February you will be, and at that point it is not a rule any more — it is a decision, made nightly, at the worst hour of the day, in the season with the least capacity to make it.

A rule installed in August is a rule. The same rule started in February is a fight.

Not four things. One.

Here is the criterion for picking well, and it is the whole instruction: choose the thing you would still do on a bad day.

Not the ambitious version. Not the one that looks best written down. The one that survives a Tuesday in November when it is raining, you slept badly, and nothing is going right. If it only works on good days, it will not exist in February, because February is made of the other kind.

For most people that is one of three: the morning light, the protein at breakfast, or two resistance sessions a week. Pick the one you can imagine doing badly and still doing.

And then hold it, alone, for the whole six weeks. Not because the others do not matter — because a single behavior that is genuinely automatic by October is worth more in February than four behaviors that were all still effortful in November.

The failure mode here is the January failure mode arriving early: taking everything on at once, in week one, at full intensity. That works for about eleven days in any month of the year.

On resistance training specifically — it is the highest-value form of movement here and outdoor activity is the thing that falls furthest in winter. I am not writing you a program in an article about daylight. The principle is that the sessions need to be indoors and scheduled by the time the weather turns, because an outdoor habit and a winter habit are not the same habit.

FRIDGE CARD

20–30 minutes outside within an hour of waking. Start tomorrow, while it is easy. Test vitamin D in September, not January. Before the fall, not after. Evening meal, fixed time, 25–30 g protein. A defined end to eating. One habit automatic before the clocks change — the one you would do on a bad day. The conditions change in October. Build now, use later.

Every autumn someone starts a large dose on the theory that more must be better going into winter.

You do not know your starting point, the response varies enormously between individuals, and vitamin D is fat-soluble, which means it accumulates rather than being cleared. The test costs less than three months of guessing, and it converts a guess into a number.

Test in September. Then dose to your number, with someone who can see it.

This is the mirror image of the January error and it is more common than you would think — the “get ahead of the holidays” plan.

October is the point in the year when the conditions are actively turning and you are stacking a restriction response on top of a declining baseline. If you are going to run a structured change, run it now, while the conditions support it, and let November and December be about maintenance rather than about willpower.

If you use one, morning is the point — light exposure late in the day pushes your circadian timing in the wrong direction and can make sleep worse.

And a box bought in December is a box bought after the decline is complete. The mechanism above runs on daylight through the autumn, not on a device deployed at the bottom.

Outdoor light in the morning, starting now, is better than a box in December, and it is free.

I am a nutrition coach, not a physician.

Everything above is about ordinary seasonal variation. It is not about clinical depression, and the distinction matters. If your winter mood involves persistent low mood most of the day most days, loss of interest in things you normally enjoy, changes in sleep or appetite that feel out of your control, or any thoughts of harming yourself — that is not a scheduling problem and it is not something to manage with morning walks. That is a conversation with a doctor, and seasonal affective disorder has real, effective treatments.

Also see a doctor rather than a calendar if you have fatigue that is disproportionate to the season, unexplained weight change, hair loss, or symptoms that persist through the summer as well. Everything described here should be seasonal.Symptoms that do not lift when the light comes back are not seasonal, and they need testing rather than timing.

I hold no position on any medication, in either direction.

Everything above is free, and the most valuable item is walking outside in the morning. You do not need to buy anything to do any of it, and if you do only that one thing, this article has done its job.

But knowing what is coming is not the same as having the structure in place when it arrives.

And a structure has to be built while conditions are favorable — that is the entire argument of this article, applied to itself. The behaviors that survive February are the ones that were already automatic in October, and the ones that were already automatic in October were installed in August and September when installing them was cheap.

That is a scheduling problem, and it has a date on it.

Twenty-one days, starting now, finishes in the first week of September — which leaves you roughly eight weeks of runway before the clocks change and the mornings go dark.

The 21-Day Hormone Reset for Women is three weeks of exactly the structure described above: three meals with protein, fat, fiber and a complex carbohydrate at a consistent time, a defined evening anchor, and 63 meals already built so the decisions are made in advance rather than at 6:45 on a Tuesday. Week 1 is cortisol and blood sugar. Week 2 is estrogen clearance and gut. Week 3 is thyroid and metabolic.

Not as a rescue. As installation — done in the eight weeks of the year when it is easiest, for use in the four months when it is hardest.

→ The 21-Day Hormone Reset for Women

$97 — against the January gym membership. You have bought that more than once and you know what happened to it, and the difference is not the money, it is the month.

Every finding, every timing, every action is above. Free. Complete.

It is for one person: you understand what is coming, and you want the structure already in place when it arrives rather than starting one in the dark.

And I have to be straight with you about the proof, because it is the strangest thing about this article.

You will notice the morning light within a week or so — most people report sleep and morning alertness shifting quickly, and that is a real and immediate return.

But the actual result of everything on this page arrives in February. Five months from now. That is an unusual thing to ask of anybody and I am not going to dress it up as a quick win.

What I will say is that the alternative is the thing you have already run twenty times, and you know exactly how far into February it gets.

It will arrive the way it always does.

The light will be bad. It will have been bad for months by then, gradually, so you will not have registered it as a change. You will be six weeks into whatever you decided on January 2nd, and it will have gotten harder in a way you cannot point to.

And you will be in the kitchen at nine at night.

Except this time, three things will already be true, and none of them will require a decision from you in that moment.

You will have been walking outside in the morning since August, which will be a thing you do rather than a thing you are attempting. Your vitamin D will be a number you know rather than a number you find out about in April. And there will be a defined shape to your evenings that was built in a month when building it cost you nothing.

None of that makes February easy. It makes February survivable at a lower cost, which is the only thing that has ever actually been missing.

You were never someone who always does this.

You were someone who scheduled the hardest thing you do all year into the six weeks when four separate systems were working against you — every year, for twenty years, on the advice of a calendar that knows nothing about daylight.

The conditions have a schedule. Now you have it too.

It is August. The light is as good as it gets.

Start now, and let February find the structure already there.

[1] Seasonal variation of vitamin D and serum thyrotropin levels and its relationship in a euthyroid Caucasian population. Endocrine Practice. PMID 29144817 — analysis of 401 patients referred with nonspecific symptoms of tiredness who had simultaneous measurement of 25(OH)D3 and thyroid function. 25(OH)D3 levels were higher in spring-summer than autumn-winter (47.9 ± 22.2 versus 42.8 ± 21.8 nmol/L; P = .02). Median TSH was higher in autumn-winter (1.9 [1.2] versus 1.8 [1.1] mU/L) but the difference was not statistically significant (P = .10). An independent inverse relationship between 25(OH)D3 and TSH was established by regression across both season groups (autumn-winter r = −0.0248, P < .00001; spring-summer r = −0.0209, P < .00001), with higher TSH found in patients with vitamin D insufficiency or deficiency compared with sufficient or optimal levels across seasons.

[2] Vitamin D deficiency in unselected patients from Swiss primary care: a cross-sectional study in two seasons. PLoS ONE. PMC4570784 — 1,682 consecutive primary care patients; summer and winter 25(OH)D concentrations differed (53.4 ± 19.9 versus 41.6 ± 19.3 nmol/L, P < 0.0001), confirmed in a subgroup of 93 patients tested in both seasons (P = 0.01). 25(OH)D deficiency (<50 nmol/L) was present in 59.2%.

[3] Seasonal variation of total and bioavailable 25-hydroxyvitamin D in the healthy adult Slovenian population. PMC11422067 — significantly lower 25(OH)D in winter (44.13 ± 17.82 nmol/L) than summer (74.97 ± 22.75 nmol/L; P < 0.001). Calculated bioavailable 25(OH)D fell from 13.11 ± 8.27 to 7.45 ± 5.66 nmol/L (P < 0.001) and the free fraction from 29.7 ± 19.1 to 17.3 ± 12.9 pmol/L (P < 0.0001). Vitamin D binding protein did not differ significantly between seasons.

[4] Praschak-Rieder N, Willeit M, Wilson AA, Houle S, Meyer JH. Seasonal variation in human brain serotonin transporter binding. Archives of General Psychiatry. 2008;65(9):1072-1078. doi:10.1001/archpsyc.65.9.1072 — [11C]DASB positron emission tomography in healthy volunteers, with scans grouped by season. Serotonin transporter binding potential — an index of transporter density, where higher binding potential corresponds to less serotonin circulating — was higher in fall and winter than in spring and summer, and was related to meteorological and astronomical data including duration of daylight.

[5] Seasonal variation of 25-hydroxyvitamin D and indices of carbohydrate and lipid metabolism in postmenopausal women. PMC8126260 — comparison between early autumn and winter revealed a marked decrease in 25(OH)D (P ≤ 0.0001) alongside decreases in insulin (P < 0.05) and the insulin resistance index HOMA-IR (P < 0.05). The authors describe the improvement in insulin sensitivity as contrary to their expectations given the fall in 25(OH)D, and hypothesize contributions from falling external temperature raising basal metabolism, or dietary factors in the pre-Christmas study period. No significant changes in lipid profile were observed.