11/09/26
4
Returning to the gym after the summer, Christmas or Easter holidays is always seen as a traumatic experience. As well as getting back to work, family commitments and so on, many people feel the urgent need to get back into shape after what they believe they have lost over the holidays. But how much truth is there in the idea of losing fitness or putting on weight during the holidays? Let’s find out with the help of some scientific studies.
First point: average (not peak) calorie intake
It is often said that Christmas and Easter lunches – but also a mid-August barbecue – lead us to consume extreme amounts of calories, even up to 6,000 kcal (these are usually lengthy meals that often overlap with snack times, aperitifs, etc.).
But this is an isolated figure that does not reflect the holiday period. The first point to note is that after meals of this kind, the feeling of fullness – mediated by the hormone leptin – reduces our need for food in the period immediately following overeating and even beyond the digestion period. The festive period, in particular, does not coincide with the working period, which lasts from a week to 15 days (for some it may reach or exceed a month, but we shall stick to the average). There is therefore a calorie increase, but it is spread over several days.
A recent study conducted in Australia (Whitton et al., 2024 – Annual and Seasonal Patterns of Dietary Intake in Australian Adults, Nutrients) indicates a weight gain of just 0.5 kg during the holiday period, and an increase in calorie intake of less than 140 kcal whilst on holiday.
Another study – Bhutani et al., 2020 – ‘Change in eating patterns as a contributor to energy intake and weight gain during the winter holiday period in obese adults’ – shows similar, and even lower, figures compared with a sample from the US, where the body mass index is significantly higher than that of Europeans.
Second consideration: leisure activities
For many people, holidays are an opportunity to relax, enjoy traditional or local dishes at their holiday destination, but also to take part in outdoor activities. Long walks on the beach, cultural visits and trips to museums, swimming in the sea (or skiing, if we’re thinking of the winter months) all ensure an increased calorie burn. For many, holidays – especially summer ones – are an opportunity for a proper ‘full immersion’ in their chosen sport: running, swimming, cycling, surfing or hiking. All of these are activities with a high or very high calorie burn.
Third consideration: actual loss of fitness
But is there an actual loss of fitness? A particularly clear study is that by Ogasawara et al. (2011): young men undertook six weeks of weight training followed by three weeks of complete rest. Muscle mass was measured using magnetic resonance imaging, assessing the cross-sectional area of the triceps and pectoralis major. After 3 weeks without training, no significant decrease was detected in either muscle cross-sectional area or strength.
A second very interesting finding comes from Hwang et al. (2017), this time involving men who were already accustomed to weight training. After 2 weeks of detraining, lean body mass measured by DXA was essentially maintained, and no reduction in leg press strength was observed.
The classic review by Mujika & Padilla distinguishes between short-term detraining (<4 weeks) and prolonged detraining (>4 weeks): it is particularly when this timeframe is exceeded that the loss of adaptations becomes progressively more significant.
So, to simplify on the basis of these data:
| Complete cessation of weight training | What to expect |
|---|---|
| ~1 week | negligible actual loss of muscle tissue |
| 2 weeks | lean mass largely preserved in studies |
| 3 weeks | there may still be no significant reduction in muscle size |
| >4 weeks | a measurable loss begins to become more likely |
| months | progressively noticeable loss of muscle mass |
Conclusions: there is no real loss of fitness, at most a loss of form
If you feel less fit, with more noticeable skin folds and less defined abs, this is due to differences in ‘pump’ (vascularisation), glycogen levels and fluid balance. A one-kilogramme difference in weight – even if it is body fat – is not yet a significant change, and returning to a more disciplined lifestyle free from excesses is sufficient to recover, provided you have an exercise or fitness routine.
