Define: bad diet
The first thing we need to do is define a ‘bad diet’.
I try to avoid labelling foods, or diets, as good or bad because they must always be considered in a great context.
A chocolate bar would not be advised if you have eaten 4000kcal and not exercised all day, but it’s different for someone trying to replenish glycogen after a full day of cycling.
Likewise, a diet of 2000kcal per day might be adequate for fat loss in one individual, yet insufficient for someone else.
There will never be good or bad diet, instead, it is always in context the individual.
In my opinion, a ‘good’ diet would be appropriately suited to achieve the individual’s goals.
But I wouldn’t call it ‘good’, I would call it ‘appropriate’.
So if someone needs 1900kcal per day to lose body fat, that’s what an appropriate intake will look like.
Let’s say it went ‘bad’ and crept up to 2300kcal, the energy deficit for fat loss was lost.
If energy expenditure was increased by 400kcal (ie. out training the ‘bad’ increases of the diet) then the energy deficit would be reinstated.
However, the current diet would still be appropriate because it is still facilitating the energy deficit required for the goal.
Therefore, you cannot out train a bad diet because the out training itself would make the diet appropriate again.
But that’s my take on a good diet, which uses the suitability to someone’s goals as the determinant.
Some people might label foods as good or bad based on the carbohydrate or fat content, whether they are processed or not, or another distinguishable factor.
In this case, it is possible to out train the bad diet.
The 1900kcal could come from these food bad food sources, making it a bad diet, but it would still create the adequate deficit for fat loss.
Even though the diet contains bad food, the energy deficit can be maintained and fat lost.
Therefore, the amount of energy expenditure was sufficient to out train the bad diet.