Weight gain after moving abroad: four factors that explain what happened

"I’ve gained weight since moving to Ireland and I don't know what changed."

This is the phrase I hear most often in my clinic. It is usually said at the end of the consultation, in a confessional tone, and is almost always accompanied by the hypothesis that the cause is a lack of willpower.

In most cases, this hypothesis is incorrect. Moving to a new country simultaneously alters several determinants of energy intake and expenditure, and these changes operate in subtle ways. This article addresses those factors.

In summary

• Moving abroad changes portion sizes, alcohol consumption patterns, seasonal appetite regulation, and daily energy expenditure all at once.

• None of these factors depend on individual discipline, and all are barely noticeable because they do not involve any conscious decision-making.

• There is also a relevant behavioural factor: the gradual interruption of self-monitoring.

• The initial recommendation is not restriction, but rather the restoration of four basic elements — hydration, fruit, regular meal times, and one change at a time.

• Rapid weight gain associated with other clinical signs requires laboratory investigation, not habit changes.

What the complaint is not

Before describing the factors, it is worth noting what clinical experience consistently shows: someone who arrives in a new country and starts trying the local food is not failing — they are integrating into the place where they have moved to.

Initial experimentation is followed by a period of overload: a new job, using English full-time, visa processes, housing, restricted budgets, and the absence of a support network. In the face of competing demands, self-care tends to be the first variable sacrificed. This is the expected choice, not an exceptional one — anyone in similar circumstances would likely do the same.

Four factors that change when moving countries

All four act simultaneously and cumulatively. It is this simultaneity that creates the feeling that "nothing changed" when, in practice, the entire food environment has shifted.

1. Portion sizes have changed, but perception hasn't caught up

Packaging, restaurant portions, and units of processed products vary between countries. However, consumption tends to remain anchored to the unit — one slice, one pot, one packet — rather than the absolute quantity.

This is a well-documented phenomenon, described in literature as the portion size effect: offering larger portions increases energy intake without a corresponding increase in the perception of the amount consumed or reported satiety. The work of Rolls and colleagues has shown this effect reproducibly under experimental conditions.

It is the quietest of the four factors, precisely because it doesn't stem from any decision. It is built into the product sitting on the shelf.

2. Alcohol has become part of the routine

In Brazil, consumption tends to be concentrated on specific weekend occasions. In Ireland, social consumption is distributed throughout the week and associated with everyday contexts — after work, Sunday lunch, work events. This distribution is a cultural characteristic of the country, and it was often this very factor that enabled the first social connections after arrival.

Two aspects deserve mention. The first is energy-related: ethanol provides approximately seven kilocalories per gram, a value higher than that of carbohydrates and proteins, and alcohol consumption is generally not counted as food intake. A standard serving of beer is close in energy content to a small meal.

The second is indirect and possibly more relevant: alcohol compromises sleep architecture, with REM sleep suppression in the first half of the night and fragmentation in the second. Lack of quality sleep is, in turn, associated with changes in appetite and higher energy intake the following day. The effect, therefore, occurs through two simultaneous pathways.

The aim of this topic is not to recommend abstinence. It is to make the effect known, as only what is known can be adjusted.

3. Photoperiod and temperature alter appetite regulation

Reduced light and falling temperatures influence appetite regulation and food preference, with a tendency toward increased demand for carbohydrate-rich foods. Studies on seasonal variation in energy intake describe this pattern, and literature on seasonal affective disorder documents, among its manifestations, an increase in appetite with a preference for carbohydrates.

It is worth keeping things in proportion: the magnitude of this effect is moderate and shows significant individual variation. Still, it is relevant for someone coming from a country with a stable photoperiod to live at a latitude where, between October and February, the commute to and from work takes place in the dark.

The practical consequence is positive: once the mechanism is recognised, it becomes possible to work with this demand rather than opposing it — warm preparations, soups with adequate protein intake, and carbohydrate sources paired with fibre, instead of isolated carbohydrates.

4. Reduction in daily energy expenditure

This is the least visible factor because it doesn't refer to workouts, but rather to the unstructured movement of the day.

Literature designates this component as NEAT (non-exercise activity thermogenesis), a term consolidated from the work of Levine: it refers to the energy expenditure associated with all activity that is not deliberate exercise — walking, stairs, going to local shops, household chores. Its contribution to total energy expenditure is substantial and varies greatly between individuals.

A change in context usually reduces this component significantly: commuting by car instead of walking, weather conditions that discourage outdoor routes, weekly shopping concentrated in large supermarkets. Daily expenditure decreases without any noticeable change in routine, and without this figure appearing in any logs.

A fifth factor, behavioural in nature

There is an additional element that is rarely addressed: at some point in the process, self-monitoring is interrupted.

One stops taking photos, avoids full-length mirrors, buys larger-sized clothes without verbalising it, and self-image becomes restricted to the camera frame in work meetings.

Weight gain, in these cases, is not abrupt — it was the interruption of self-monitoring that was gradual. The perception of change tends to occur suddenly, usually when seeing an old photo, which creates the mistaken impression that the body changed all at once.

It should be noted that self-monitoring, here, does not mean weighing oneself or numerical control. It means regaining contact with one's own image without it being a cause for punishment.

Where to start again: four initial measures

This article does not propose a meal plan. It proposes the restoration of what is usually abandoned first — and which, for that very reason, most quickly restores the sense of self-care.

1. Hydration

This is the simplest measure and the one with the lowest adherence, mainly because tea with milk and coffee do not replace water intake, even though they are often counted as such.

The operational recommendation is to keep a full bottle at your workstation. (Irish water has specific composition characteristics that deserve their own treatment, the subject of next week's article.)

2. Fruit

Daily consumption, with minimal preparation.

This is the item that usually disappears first after immigration, for three combined reasons: higher relative cost, unavailability of familiar varieties from the home country, and a lack of familiarity with the local offering. The interruption happens without an explicit decision.

The guidance is to prioritise what has stable availability and pricing throughout the year: bananas, apples, oranges, and frozen berries — the latter generally costing less, with no loss to spoilage and easily incorporated into the first meal.

The initial goal is not to reach daily portion recommendations. It is to re-establish consumption.

3. Three meals at set times

The pattern described in consultations is one of an unstructured routine: the first meal replaced by coffee, lunch shifted to an indeterminate time, and the first structured meal occurring late at night.

The initial recommendation does not focus on the composition of the plate, but rather on the existence of three defined times: morning, midday, and night. Using an alarm is acceptable and often necessary in the initial phase.

Clinical observation is consistent: the lack of control over the evening meal tends to reduce spontaneously when the previous two meals are re-established.

4. One change at a time

This is the most important of the four, as it is the one that prevents the relapse pattern.

The habitual behaviour, when one becomes aware of the problem, is the simultaneous implementation of multiple restrictions — excluding gluten, excluding sugar, skipping dinner, using so-called detox products, and adopting prolonged fasting, all on the same day. This model has low sustainability: adherence usually stops within a few weeks, and the abandonment adds a layer of guilt that makes the next attempt harder.

A process that took years to establish is not reversed in a week, and there is no need for it to be. It is recommended to implement one change, consolidate it until it becomes automatic, and only then introduce the next.

When to investigate rather than intervene in habits

This distinction is part of professional conduct.

Rapid weight gain, accompanied by other signs — hair loss, cold intolerance, persistent changes in bowel habits, fatigue that doesn't improve with adequate sleep — is not a case for behavioural intervention. Laboratory investigation is indicated.

The course of action is to see a General Practitioner (GP). If you have doubts about how to frame the request in English, this is a frequent and legitimate question that I regularly advise on.

Final considerations

There is no need to return to the pre-immigration state. That context did not include your current job, the language used daily, or the ongoing adaptation process.

The reasonable goal is different: to re-establish contact with your own body and restore the basics at a sustainable pace. It is a more achievable goal than it usually seems.

References

The references below are listed by author and topic. It is recommended to consult the sources directly for deeper insight.

• Portion size effect: Rolls, B. J. et al. — increase in energy intake associated with larger portions, without a corresponding increase in the perception of quantity or reported satiety.

• Energy density of ethanol: approximately 7 kcal/g, higher than carbohydrates and proteins.

• Alcohol and sleep architecture: Ebrahim, I. O. et al. — reduction in sleep latency, REM suppression in the first half of the night, and fragmentation in the second.

• Seasonal variation in intake: de Castro, J. M. — description of seasonal rhythms in nutrient intake and meal patterns. Literature on seasonal affective disorder (Rosenthal, N. E. et al.) documents increased appetite with a preference for carbohydrates among the manifestations of the condition.

• NEAT: Levine, J. A. — conceptualisation of non-exercise activity thermogenesis and its contribution to total energy expenditure.

• Self-monitoring: Burke, L. E. et al. — association between consistent self-monitoring and better weight management outcomes.

Consultations

I am a Brazilian nutritionist and I treat Brazilians living in Ireland. The follow-up considers the local context — the markets where you shop, the weather conditions, and the work routine of those who live here.

Book a consultation to structure your nutrition based on the routine you have today.