Ein paar Weihnachtsstudien

1. Effectiveness of a brief behavioural intervention to prevent weight gain over the Christmas holiday period: randomised controlled trial

Objective To test the effectiveness of a brief behavioural intervention to prevent weight gain over the Christmas holiday period.

Design Two group, double blinded randomised controlled trial.

Setting Recruitment from workplaces, social media platforms, and schools pre-Christmas 2016 and 2017 in Birmingham, UK.

Participants 272 adults aged 18 years or more with a body mass index of 20 or more: 136 were randomised to a brief behavioural intervention and 136 to a leaflet on healthy living (comparator). Baseline assessments were conducted in November and December with follow-up assessments in January and February (4-8 weeks after baseline).

Interventions The intervention aimed to increase restraint of eating and drinking through regular self weighing and recording of weight and reflection on weight trajectory; providing information on good weight management strategies over the Christmas period; and pictorial information on the physical activity calorie equivalent (PACE) of regularly consumed festive foods and drinks. The goal was to gain no more than 0.5 kg of baseline weight. The comparator group received a leaflet on healthy living.

Main outcome measures The primary outcome was weight at follow-up. The primary analysis compared weight at follow-up between the intervention and comparator arms, adjusting for baseline weight and the stratification variable of attendance at a commercial weight loss programme. Secondary outcomes (recorded at follow-up) were: weight gain of 0.5 kg or less, self reported frequency of self weighing (at least twice weekly versus less than twice weekly), percentage body fat, and cognitive restraint of eating, emotional eating, and uncontrolled eating.

Results Mean weight change was −0.13 kg (95% confidence interval −0.4 to 0.15) in the intervention group and 0.37 kg (0.12 to 0.62) in the comparator group. The adjusted mean difference in weight (intervention−comparator) was −0.49 kg (95% confidence interval −0.85 to −0.13, P=0.008). The odds ratio for gaining no more than 0.5 kg was non-significant (1.22, 95% confidence interval 0.74 to 2.00, P=0.44).

Conclusion A brief behavioural intervention involving regular self weighing, weight management advice, and information about the amount of physical activity required to expend the calories in festive foods and drinks prevented weight gain over the Christmas holiday period.


2. The Christmas holidays are immediately followed by a period of hypercholesterolemia

Celebrating Christmas is associated with higher levels of total and LDL cholesterol.

Celebrating Christmas is associated with a higher risk of hypercholesterolemia.

A diagnosis of hypercholesterolemia should not be made around Christmas.


Background and aims

We aimed to test the hypothesis that levels of total and low-density lipoprotein cholesterol are increased after Christmas and that the risk of hypercholesterolemia is increased after the Christmas holidays.


We conducted an observational study of 25,764 individuals from the Copenhagen General Population Study, Denmark, aged 20–100 years. Main outcome measures were mean total and LDL cholesterol levels. Hypercholesterolemia was defined as total cholesterol >5 mmol/L (>193 mg/dL) or LDL-cholesterol >3 mmol/L (>116 mg/dL).


Mean levels of total and LDL cholesterol increased in individuals examined in summer through December and January. Compared with individuals examined in May–June, those examined in December–January had 15% higher total cholesterol levels (p < 0.001). The corresponding value for LDL cholesterol was 20% (p < 0.001). Of the individuals attending the study during the first week of January, immediately after the Christmas holidays, 77% had LDL cholesterol above 3 mmol/L (116 mg/dL) and 89% had total cholesterol above 5 mmol/L (193 mg/dL). In individuals attending the Copenhagen General Population Study in the first week of January, the multivariable adjusted odds ratio of hypercholesterolemia was 6.0 (95% confidence interval 4.2–8.5) compared with individuals attending the study during the rest of the year.


Celebrating Christmas is associated with higher levels of total and LDL cholesterol and a higher risk of hypercholesterolemia in individuals in the general population. Thus, a diagnosis of hypercholesterolemia should not be made around Christmas, and our results stress the need for re-testing such patients later and certainly prior to initiation of cholesterol-lowering treatment.

3. How COVID-safe Santa can save Christmas

(…) Visiting every house on earth, including regions where COVID-19 is eliminated and others where it’s out of control, presents a significant infectioncontrol challenge. Applying our traffic light system4 Santa would be coming from a low-risk ‘green’ jurisdiction given Santa Clause Village closed its borders more than 1,000 years ago and has had no reported cases of COVID-19.

Therefore, as the likelihood of Santa being infected with coronavirus before setting out on Christmas Eve is extremely low, he will not be asked
to quarantine on arrival in each jurisdiction. Nevertheless, given the high-risk nature of his job, he will require a negative test before flying. Additional precautions to adopt include making Santa’s sleigh covid-safe with fibreglass screens, and installation of a handsanitiser dispenser. And, along with Santa, the reindeer will be masked this year. We acknowledge that outdoor masks on reindeer might seem excessive and not evidencebased, but we feel this is a unique situation where being extra cautious makes sense.
Families can play their role in protecting this important frontline worker by staying at home – in bed. Santa assures us he only enters houses where children are sleeping so person-to-person contact should not be a problem. We can also help to keep him safe by making sure that if we leave him milk/brandy and cookies – which perhaps we should not given his aforementioned weight issue – we should use disposable cups and plates and have hand sanitiser on the table.
In the unlikely event that there are leftover brandy or biscuits, Mum and Dad should resist the temptation to finish them off and instead safely dispose of them. (…)

4. Too cold for warm glow? Christmas-season effects in charitable giving

This paper analyzes seasonal effects and their potential drivers in charitable giving. We conduct two studies to analyze whether donations to the German Red Cross differ between the Christmas season and summer. In study 1 we find that in the pre-Christmas shopping season prosocial subjects almost donate 50% less compared to prosocials in summer. In study 2 we replicate the low donations in the Christmas season. In an extensive questionnaire we control for several causes of this effect. The data suggest that the higher prosocials’ self-reported stress level, the lower the donations. The higher their relative savings, the lower the giving. Our questionnaire rules out that “donation fatigue” matters. That is, donations do not depend on the number of charitable campaigns subjects are confronted with and their engagement in these activities during Christmas season outside the lab.