Just for grins and giggles, I did some quick googling.
Depending on where you look, the recommended caloric needs of a one year old range from 1000-1300 calories per day.
According to Kellymom (http://www.kellymom.com/nutrition/milk/change-milkfat.html), there is an average of 22 calories per ounce of breastmilk. 1000-1300 calories is equivalent to 45.5 - 59 ounces of breastmilk. So in order for a 1 one year old to consume 75% of their 1000-1300 calories per day, they would need to consume 34-44 ounces of breastmilk per day.
I don't know about anyone else, but at one year postpartum I am 100% sure, beyond a shadow of a doubt, that my body was NOT capable of producing up to 44 ounces of milk.
The remaining 25% does NOT translate to a lot of solid food. This is just a few examples of toddler appropriate snacks:
Half a banana = 100 calories
10 grapes = 34 calories
Half an avocado = 161 calories
Half a cup of sweet potato = 90 calories
5 Saltine crackers = 63 calories
1/4 cup whole wheat pasta = 43 calories
So.... half a banana, a quarter of an avocado, 5 saltine crackers and 10 grapes is roughly 277 calories. A whole banana and a handful of pasta is 243 calories. My daughter ate WAY more than that in one day, and quite honestly, withholding solid food from a 1 year old to force them to nurse more is rather cruel, in my opinion.