If you break it down by the numbers, it seems to be closer to the 3K than 4,5K, but the variation can be huge depending on what drinks and snacks there are.
According to research from the Calorie Control Council, the average
American may consume more than 4,500 calories and a whopping 229 grams
of fat during a typical holiday gathering from snacking and eating a
traditional Thanksgiving dinner with turkey and all the trimmings.
Here's the detail:
The average holiday dinner alone can carry a load of 3,000 calories.
And many nibble through another 1,500 calories, downing appetizers and
drinks before and after the big meal. Combined, that's the equivalent
of more than 2 1/4 times the average daily calorie intake and almost 3
1/2 times the fat -- with 45 percent of calories from fat. The average
person may consume enough fat at a holiday meal to equal three sticks
of butter.
This is the original source.
If the question is about the number of calories in a typical Thanksgiving meal, we can try to calculate the calories for each individual food using the USDA values.
What constitutes a traditional Thanksgiving meal?
Turkey seller Butterball, itself a holiday institution for many
families for years, recently conducted an online regional holiday
survey to collect data about Thanksgiving preferences. It found the
top five side dishes Americans must have on their Thanksgiving table
are mashed potatoes (95 percent), cranberry sauce (81 percent),
candied sweet potatoes (63 percent), green bean casserole (59 percent)
and gravy (41 percent).
Their approximate values according to the USDA:
- Turkey: 189 c / 100 gr
- Mashed potatoes: 88 c / 100 gr
- Yams (no sugar): 118 c / 100 gr
- Cranberry Sauce: 150 c / 100 gr
- Pumpkin Pie: 243 c / 100 gr
If someone has 300 gr of Turkey, that alone is almost 600 calories (without the filling or gravy), add a couple of pumpkin pies, you are already over the thousand. With rolls, alcohol and snack you might get to the 4500, or not. There is a lot of variation.
In both cases, the single meal is over the daily recommended ingestion, which is around 2000-2500 calories a day.