Can having too few calories slow weight loss?

I was talking to the dietitian at my gym and she talked my girlfriend and I into a free summary session (i.e. sales pitch). She went over our last week’s caloric intake and she said that my gf wasn’t losing weight because she wasn’t eating enough calories. I’m sure I misheard her, but that was the gist of what she said. Isn’t weight purely a function of caloric intake? Eat less, weigh less, right? I asked her to clarify, and she said that eating quality calories (she didn’t define “quality”) helps you tone faster and lose weight faster.

Given the amount we work out, my gf in particular, was not losing weight because she was not getting enough calories and she was entering starvation mode, meaning, her body was more disposed to holding on to calories as fat. In my case, I was building too much muscle to realize any weight loss (though I assume I lost fat because for kicks I tried on my college graduation suit and it still fit.). She said that we could have better measurements if we did the free health assessment, but I wasn’t in the mood for a personal training sales pitch, and those guys are absolutely brutal with those calipers (seriously, the last girl gave me a bruise).

All of this doesn’t sound right. What’s the straight dope?

Well, five pounds of pure fat is about the size of a sandwich loaf of bread, according to my mom’s dietician. An equivalent weight of muscle is around half that much. Muscle is much denser than adipose. So yeah, if you’re training really hard, you can lose fat, gain muscle, and not really see the scale move much. You’ll see the difference in the size of your body, though, which is why most healthy living/diet sites will tell you to worry more about your measurements than your weight.

As for your girlfriend, yeah, you can eat too few calories to lose weight. Weight is purely a function of the difference between calorie intake and calorie burning. Which is to say, it’s a function of your metabolism. That’s why some people can eat like they’ve got a hollow leg and stay skinny as a rail and other people can look at a fattening dish and their asses expand.

Part of your metabolism is genetic, part of it is situational. Our bodies are adapted for survival, and part of survival is making it through periods of famine on much fewer calories than we’re used to. How do our bodies do that? Well, they slow down the metabolism, to wring as much use as possible out of the calories that are available. This is called starvation mode, and it makes it hard to lose weight because, well, your body is trying like hell to hang on to everything it can so you’ll live through the famine.

If you look at any of the calculators designed to show you how many calories you should eat daily to maintain or lose weight at a given pace, there’s a lower limit on those. That lower limit is there to keep you from throwing yourself into starvation mode and stalling out your weight loss.

You need to eat in order to lose weight. It sounds contraindicative, but it’s true. If your body doesn’t get enough calories over a period of time, it will go into starvation mode and hang onto every calorie you give it. Eating keeps your metabolism running and your body fueled. You burn a certain amount of calories every day just by existing. This is your BMR (Base Metabolic Rate). You need to eat at least this much every day just to survive. If you excercise, you need to eat back those calories too. Eating quality calories is key to losing weight. Beans, whole grains, vegetables and fruit keep you feeling fuller longer with less calories. You can find more information about it on


Starvation mode

Starvation mode is a state in which the body is responding to unhealthily low caloric intake levels. The body becomes more efficient at using energy and burns lean tissue and muscle in order to conserve fat reserves.[1] If one’s goal is weight loss, cutting calories below a certain level is both dangerous to one’s health and counterproductive.[2]

IANAD but I thought to enter starvation mode you have to be fasting/consuming almost zero calories.

Is there an exact “tipping point” to entering starvation mode, or can you be slightly in starvation mode by eating slightly too few calories?

Hmmm…so really fat people would still have to consume a whole bunch of calories to keep the fat burning going, right? Man, that does sounds counterintuitive.

Starvation mode is only minor. Studies have shown people that yo-yo diet lose about 250 calories MORE a week than those who don’t yo-yo and go into starvation mode.

250 calories is a little more than 2 peanut butter cups. And that’s PER WEEK. That is not enough to notice any difference in weight except at a tiny level.

It’s ludicrous to think if you starve, you won’t lose weight. I can put you in room, lock you in and feed you bread and water and in one month you WILL lose about 1/3 of your body weight.

People in WWII starved and they lost weight. I can absolutely guarantee you, if you’re not losing weight you eat to much. I have a kick ass body and I eat whatever I want, it’s all calories IN and calories out.

The problem is your body compensates, your metabolism ONLY changes through hard work out. We’re talking at minimum 1 hour of aerobics with your pulse at 60% (at least) of your theoretical maxium. If you don’t do that you won’t lose weight through exercise

So starvation mode is true, but the amount would only make a difference of about 3 pounds a year. And no one can look at you and say “Gee you look thinner,” if you’ve only lost three pounds.

I was involved in a University Of Chicago study with weight, so this is why gimicks because gimmicks sell. We discoved when we had people keep food journals, then went through their garbage, then confronting them, people were eating about 40% MORE than they thought.

We had registered dieticians estimate calories content. The closest to correct was 27% OVER what she said. In otherwords, her calulations were more than 1/4 MORE than she thought.

Why would the human body not have evolved to “make as much use out of the available calories” anyway?

“Starvation mode” is a myth, IMO and a simply an excuse for people to give in to binges and cravings.

I think there’s some merit to the “Starvation Mode” theory. Of course, I’m not a dietitian, and I don’t have any cites handy, but it makes sense that one’s metabolism would slow down if energy intake were to be reduced. By slowing the metabolism down, the body is responding to the decreased energy intake by correspondingly reducing energy output.

So is there a starvation mode? ISTM that there is an optimal way to lose weight and retain lean body mass. I suppose I could try the concentration camp diet, but I would probably be too frail to really enjoy life.

As far as I know, it works like this:

Assume your BMR rate is to burn 2000 calories per day.
Eating 1500 calories a day is the recommended way to lose weight.
Eating 500 calories a day is “starvation mode” and will lose weight in muscles.

The trouble is that for woman, those numbers are much closer together, and dropping 500 calories per day is “starvation mode”.

Yep, this is exactly how it was explained to me.

Here’s an explanation that may make more sense, and is probably more accurate physiologically.

Ketones in urine indicates the breakdown of your own muscle tissue to meet current energy needs instead of using calories taken in through consumption of food. You can get strips to pee on that will let you know how much ketones are in your urine. When I was pregnant and diabetic, my dietician had me keep track exactly of my caloric intake and I used the strips to find when I was passing ketones. That allowed me to establish a minimum caloric intake so I could stop losing weight.

You can use the strips to find when you are breaking down your own muscle tissue. It may be that you need to avoid passing any ketones, or just avoid passing too many in order to avoid “starvation mode”.

Haha, last time I said this folks at the gym looked at me like I was the biggest asshole in the world. Starvation mode is really just a weird peak where you’re eating just under the amount of calories you need and not doing the right exercise to direct it in what calories to get.

The fact is that exercise negates starvation mode. If your body needs 2000 calories and you only give it 500, it’s going to eat 1500 from your body. Now, it’s true that it’ll switch to muscle instead of fat, and decreased muscle mass will require a lower BMR, but here’s the kicker: so long as you’re exercising those muscles, it won’t eat them. It will eat fat. Your body would much rather go into emergency fat reserves than break down a muscle in need of repair.