Does UNDEReating slow weightloss?

March 9, 2005 10:57 AM

I keep hearing that while you're trying to lose weight, you should be careful not to UNDEReat. True?

The argument goes something like this: if you consume less than X number of calories a day, your metabolism will slow down, and you won't burn as many as you work out. Now I know there are important reasons not to starve yourself, but I don't understand that particular argument. Lets say I do the same stuff every day -- walk up and down the same steps, carry the same briefcase, etc. Surely it will take the same amount of energy each day to complete these same tasks. So I should be burning the same number of calories each day, regardless of how much I eat.

It would be one thing if people said, "but you won't be able to do the same amount of work," but they don't say that.

So what gives?

I'm asking, because my appetite has gone way down. I am eating as much as I need to eat to feel full, and then stopping. But when I calculate the number of consumed calories, it's less than I "should" be getting. Still, I don't feel hungry for more, so it seems perverse to eat more -- especially when I'm trying to lose weight. I'm not feeling tired or anything, either.

posted by grumblebee to Health & Fitness (17 answers total)

Your body spends calories just to keep itself alive and to fix itself. In fact, that's most of what you burn. After all, sleeping burns about 70 calories an hour (so 560 calories per night). I assumed that the reduction in calorie burning is taken from those keeping itself alive functions. That is, your body might fix itself slower and so on.

If, however, you're feeling fine and eating so you're not hungry, I would guess you're not eating too little. If you start to notice that you're not feeling as healthy or your weightloss slows down, you might try at least for a short time uping your calorie intake. But, if you're truly worried about your health or whatever, ask a suitable professional (doctor, dietitian, etc).
posted by skynxnex at 11:12 AM on March 9, 2005

I agree with the last post. I started adding up the number of calories I was actually eating on South Beach and it was far less than the 2000 calories per day for a normal diet, and even less than the 1500 calories per day typical of a lot of diets. I've lost 42 lb. in just over two months.
posted by Doohickie at 11:15 AM on March 9, 2005

It's the basal metabolic rate — the base amount that your body uses just to keep you alive — that is majority of the number of calories burnt through the day (over 2000 for a typical male). So, if you go into "starvation mode," you burn substantially less calories. That's one reason why weight training is so effective for weight management, as it actually increases your BMR.

That said, it would be nice to have some guidelines as to when starvation mode kicks in... I've seen varying accounts and it all seems rather fuzzy. Somewhat tangentially, there has been some research that skipping meals can be beneficial.
posted by brool at 11:15 AM on March 9, 2005

your metabolism will slow down, and you won't burn as many as you work out

That's only true if you're bonking consistently. As brool pointed out, your basal rate will decline if you go into conservation mode. But if you're in conservation mode you won't be able to hit your exercise goals. Your body just says "no" and you can't continue because the energy isn't there. The symptoms are obvious. I can't emphasize this enough-- you'll know if it's a problem.

So only adjust your calories upward if you crap out. "Starvation mode" is obvious to someone who's exercising. It's really only a problem to people who are eating almost nothing, and it's more often just used as an excuse as to why someone's diet failed.
posted by Mayor Curley at 11:41 AM on March 9, 2005

I think it's more to do with number of meals than number of calories. After I started eating 5 meals a day my weight started going down. I was eating fewer calories and feeling less hungry.
posted by sid at 11:55 AM on March 9, 2005

Yeah, huge gaps between meals will screw with your metabolism. You should eat frequently with small portions.
posted by knave at 12:01 PM on March 9, 2005

If you don't eat enough and do a proper workout in the gym (including weight training), trust me that you will feel the lack of energy. I once made the mistake of giving one of those silly low-carb diets a whirl and hitting the weights.

Damn, I nearly passed out lifting about 70% of the weight I normally handle. I felt unbelievably drained.

Eat enough; eat often. I've felt the best when I was eating 5-6 times a day. (Which, thanks to my job, I can't do so often any more.)
posted by madman at 12:18 PM on March 9, 2005

Thanks, folks. I figured I should just "listen to my body." If I can piggyback on my own question, what do you guys think of the "you can't lose weight and build muscle at the same time" controversy?

Currently, I'm just trying to lose weight. In six months or so, I should be at my goal. I was planning to wait until then to start building muscle. Wise? Unwise?
posted by grumblebee at 12:34 PM on March 9, 2005

That's one reason why weight training is so effective for weight management, as it actually increases your BMR.

But not by very much, of course. Needs bugmenot…sorry.

Also, see the second point on this page.
posted by jikel_morten at 12:38 PM on March 9, 2005

In six months or so, I should be at my goal. I was planning to wait until then to start building muscle. Wise? Unwise?

I see no reason to hold off on strength training. If you add it to your current exercise regime, you'll burn more calories. And if you're very out of shape now, adding muscle might slow your weight loss slightly, but you'll still lose weight. Basic strength training won't put on a lot of muscle mass; that's something to be more concerned about if you're really trying to bulk up.
posted by mr_roboto at 12:52 PM on March 9, 2005

"Starvation mode" is obvious to someone who's exercising.

Not if you have a certain type of manic personality and willpower. I know that my stubborn brain regularly forces my body beyond what it should do, as far as exercize and forgetting to eat right, and I've known other people who seemed to fit the same bill. I knew a serious, talented martial artist who overtrained constantly and rarely ate well and, despite having amazing physical ability, never could lose that little paunchy gut. From experience, I'd rather exercize and eat too much than eat too little when I'm trying to lose weight.
posted by Shane at 12:57 PM on March 9, 2005

I think it's because you eat more if you are hungry, it takes time for your body to feel full, about 20 minutes, which is more time than it takes to eat.

I've seen a number of diets recommend actually increasing the amount you eat to include snacks between meals, and this is the stated reason.
posted by xammerboy at 1:39 PM on March 9, 2005

grumblebee: You'll know if you need to eat more. There was a period when I routinely forgot to eat for long stretches (I think 3 days was the max), but I wasn't using the calories. When I needed the energy, I immediately felt like eating a steak. Hard to explain, but you will know if you aren't eating enough.

madman: The low and no carb diets are only low and no carb if you don't do a lot of exercise. You can be on Atkins and still eat plenty of carbs, you just need to know how many you need. It isn't the no carb all meat diet, like many people seem to think it is.
posted by bh at 2:40 PM on March 9, 2005

As far as weight training while trying to lose weight, I think it's a great idea. Although previous posters pointed out that the extra muscle won't cause a huge increase in your BMR, they won't hurt either. But more importantly, if you're aiming to lose a significant amount of weight, you'll probably want to replace some of that fat with muscle so as to avoid saggy, wrinkly skin. Some stretch marks and loose skin might be unavoidable, but adding muscle definition and tone can be a big cosmetic help, as well as having long-term physiological benefits.
posted by Bella Sebastian at 2:45 PM on March 9, 2005

bh: I disagree that grumblebee will necessarily know when he needs to eat more. My brother went through a two-year lethargic period while between high school and college. He was scrawny and sleepy all the time. Eventually he realized he wasn't eating enough (after two years), and he changed his habits. More food brought more energy.

A lot of people think they need 2,000 calories per day, because that's the baseline the FDA uses in its calculations. It's a good guideline for a moderately active, average metabolism, average size male who's not looking to gain or lose weight. I only need about 1,300 to 1,600 calories per day as a moderately active, slow metabolism female. To lose weight I need to cut down to about 1,000 to 1,200 calories per day.

So, grumblebee, are you sure about the amount you "should" be getting? Maybe it's lower than you think?
posted by croutonsupafreak at 3:35 PM on March 9, 2005

croutonsupafreak: I would argue that your brother's lethargic period should have been warning enough, but I see your point. My low consumption period was during a serious illness, and whenever I would forget to eat after I was healed, I would feel it. I've found that when I exercise, I always know when I'm undernourished.

Good call on the FDA caloric recommendations.
posted by bh at 5:00 PM on March 9, 2005

Third the FDA point. You have to find out how many calories you use in a day. I'm a guy, 6'2", and it wasn't until I went below 1800 calories a day that I started losing weight.

For the most lucid, pragmatic explanation of how lose weight, see the ever popular Hacker's Diet.
posted by 4easypayments at 7:32 PM on March 9, 2005