The Danger of Undereating

In the comments of yesterday’s post, Jacqui asked the excellent question, wondering if I am undereating:

Isn’t your average man supposed to take in about 2,500 calories? And then if you are running a whole lot on top of that, then surely around 1,700 is a pretty serious calorie deficit.

That’s a great question, because it’s a real problem with people who are trying to lose weight, especially runners and people doing other types of sports and cutting back on calories. It’s also a question I can’t answer definitively, and will have to monitor myself closely every day to really answer.

First, the caloric requirements: while it’s true that many men need 2,500 calories, every calorie calculator I’ve used says that a 34-year-old man who is 5′11″ (I’m actually in between 5′11″ and 6′0″ I think) and 190 lbs (I’m 186.6 this morning!) needs 1900 calories, just living everyday life. That’s the level I’d have to eat to maintain my current weight. Edit: I should add that when I started losing weight, my caloric requirement was actually 2,500, as I was more than 30 lbs. heavier at the time.

If you add running and other exercise, that number goes up. If I run three miles (my level this week, as I’m recovering from the marathon), you can add nearly 400 calories to that number — let’s say 2280 for that day. Strength training is less, especially as I’m starting really light. When I start to run more, I will need more calories to maintain my weight — some days I burn off 1,000-2,000 calories in a run.

However, as I’m looking not to maintain my weight but lose weight, I am aiming for a calorie deficit. It’s the only way to lose weight. More specifically, I’m looking to lose fat, but you can’t lose only fat — you always lose some combination of fat, muscle, and other tissue. I hope it’ll be mostly fat, and I’m hoping that my strength training will help ensure that I’m retaining muscle and losing fat, but it’s never 100% fat.

How big of a calorie deficit should I have? Every article I’ve read says that you should aim for 1-2 lbs. a week if you’re trying to lose weight, and no more. There might be an exception for people who are really large, but in general you shouldn’t lose to much as that can be unsafe and unhealthy. So 1-2 lbs. a week averages out to a deficit of about 500-1,000 calories each day (you need to have a deficit of 3,500 calories to burn a pound of fat, so 3,500 for one week would be 500 per day). That’s my goal.

So if I don’t exercise, I would try to only eat 900-1,400 per day, as my non-exercise maintenance requirement is 1,900, right? Well, not really. Experts say that men need to take in a minimum of 1,500 calories a day, or they probably aren’t getting enough nutrients (for women, the minimum is 1,200 per day). So I can’t drop below that number. I’m aiming for about 1,600-1,800 on non-exercise days. On days when I run, I can eat a little more, and when I run a lot, I need to eat more. Yesterday, I took in 1,700 calories but only burned like 50 in exercise for a total of 1,950 — that’s a deficit of 250, or a little less than my goal, but that’s OK. I don’t have to hit the goal every single day.

But we should also remember that most of these numbers are generalizations. Two people of the same calorie requirements can eat exactly the same foods and do exactly the same exercise and not lose weight the same way. So I need to really monitor myself to make sure that I’m not undereating. I also am monitoring my protein intake and fat intake to ensure that they’re adequate.

How will I monitor myself to make sure I’m not undereating? Several ways:

• Make sure my calorie intake isn’t below 1,600 each day.
• See how my energy is during the day — logs are good for this.
• Monitor myself closely during exercise for fatigue, sluggishness, etc.
• Monitor my weight loss — not daily, but weekly — ensure that I’m not losing more than 2 lbs. a week on average. I may lose more than 2 lbs. in one week, but if that trend continues for more than a week, I’m probably undereating.

If I notice any problems with any of the above, I’ll make adjustments. That’s the benefit of having a log.

And another key: I have you guys! People who show concern, like Jacqui, will keep me honest and make sure that I remember to monitor myself. Thanks Jacqui and everyone else who’s helping me along the way!