I know that people like to take shortcuts when building apps for themselves but, you are taking a direction that is going to cause you a great deal more work than you think as well as being a real pain to expand or change. Having a form with a checkbox for each food item means having to modify the form and the table every time you want to add a new food item. This design also means that you need to manually sum the fat grams by adding the fields together, both on the form to show a total and also in any query or report you want to build. This calculation also needs to change if you add a new food. Your design also doesn't allow for multiple servings. What if you're having a really bad day and eat three bags of chips?
You have a many-to-many relationship between your day and the items that you consume. Therefore you'll need three tables to store this information properly.
tblMyDays
DailyID (autonumber, primary key)
FullName (your spouse might also want to use the db)
TodaysDate (defaulat to Date())
(you should make a unique alternate index that includes FullName and TodaysDate so that you can only create one record per day per person)
tblFoods
FoodId (autonumber, primary key)
FoodName
ServingSize
FatGramsPerServing
tblDailyFoods
DailyID (primary key, field1)
FoodID (primary key, field2)
NumOfServings (default to 1)
To implement this solution, you'll need a mainform to display the information from a query based on tblMyDays that contains a subform based on tblDailyFoods. The subform will contain a combo that is based on a query of tblFoods. You choose a food item from the combo. The default number of servings should be set to 1.
With this structure, simple queries will calculate whatever you need to calculate.