Recent research shows that new parents (with children 5 or under) have about an hour/day less of physical activity. Perhaps not surprisingly, this results in mothers (though not fathers, for some reason) being significantly fatter than women who are otherwise similar (age/race/ethnicity/income etc.). Mothers also eat more fat and sugary drinks than non-mothers, for about 400 extra calories/day.
I have noticed this same phenomenon in myself. I exercised most days while I was pregnant, even in the last few months, and was pretty active pre-pregnancy (I went to the gym at least 4 days/week). However, since little R was born I have had a lot of trouble motivating myself to exercise. I did go to the gym tonight (because I asked B to help me go, and he made me), but it's the first time I have had any exercise whatsoever in about a week. We have lived here for over a month, and I have been to the (nice, onsite, free) gym maybe 5 times.
The problem is that I only have a limited amount of willpower. All day long, I must draw on my willpower reserves to do things that are somewhat unpleasant: changing poopy diapers, getting up at 2 am to feed little R, cleaning up after she "ate" and spread food all over herself, her high chair and the floor. And while playing with her or dressing her isn't intrinsically unpleasant, I have to do those things on her schedule, rather than when I feel like it.
By the time the day is over at 8 pm, I am somewhat physically tired, but more importantly, my willpower has all been used up. All I want to do is surf the internet, watch movies or do something else requiring very little brainpower (even reading a book is often too taxing, sad as that is). If B needs something, I am able to summon my willpower reserves and help him with it, but this is only because I am so fond of him (everyone else is out of luck). Apparently I am not equally fond of my physical health.
Also, because I usually feel mentally tired, I want to "pamper" myself and give myself little indulgences. This impulse is fine, but unfortunately the easiest way to indulge myself is to eat fatty or sugary (or both! chocolate I love you) food, so I end up eating lots of unhealthy, caloric things. Eating cucumber slices with vinegar, while tasty, just doesn't have the same connotation of a treat. I think the only reason I am not really fat is because I'm breastfeeding.
I am not sure exactly what to do about my problem. I don't want to be fat and unhealthy. On the other hand, there is no way to make parenting an infant less demanding of one's willpower. In fact, as she grows to be a toddler, everything I have heard leads me to believe that the reverse is true. Convincing myself that exercise is fun and eating vegetables is decadent would be the best solution, but since I have hated all forms of physical activity since I was in grade school and would live on ice cream in a perfect world, this outcome is unlikely.
Probably the best thing to do is: 1. keep limited amounts of "treats" in the house (since I can't go out after 8 pm anyway) and 2. delegate the willpower necessary for my exercise to B. He will just have to make me go exercise, like today, unpleasant as that is. (Acting like a stern parent to an ungrateful and whiny spouse is not on anyone's wish list.) Sorry B! At least he will benefit if I am in shape, so his effort won't be entirely wasted.