Starvation Mode
What is it?
I receive more emails about the dreaded “starvation mode” than any other topic. For those who don’t know, depending on who you ask, the starvation mode is a metabolic crash in response to consuming too few calories. Go figure that this doesn’t apply to anorexics who continue to lose weight even when calories are much lower for extended periods of time. <insert sarcasm>Fat loss is not a linear process. Plateaus are not only possible… they’re probable. Therefore they should be expected. By the time I’m done with this section, I’m hoping that each time a plateau occurs, you’re not running around frantically trying to fix your ‘broken metabolism.’
If I were to ask a room full of people what their definition of the starvation mode is, I’m sure I’d receive a wide array of answers. The common ones would likely go something like this:
It is when your metabolism shuts down by eating less than 1,200 calories.Or…
It is when your metabolism slows down so much in response to a calorie deficit that you can’t lose more weight or you actually gain weight.In actuality, there is some truth to what people are calling the starvation mode. There’s also a whole lot of fiction and ignorance thrown into the mix as well.
Here’s the low down…
In the research, what many call the starvation mode is typically referred to as adaptive thermogenesis. I prefer the latter simply because it implies that it’s a process rather than an immediate response to dieting. It’s a messy term though so I’ll use starvation mode or starvation response throughout this section.
The starvation mode isn’t something that happens in the flick of a switch. It’s a continual adjustment your body undergoes in response to an energy shortfall. It’s your body’s way of conserving itself during times of famine. Thank your local caveman.
This adjustment leads to a reduction in energy expenditure. Remember, total energy expenditure is a combination of basal metabolic rate, energy expended through activity, and energy expended digesting food.
Its Impact On BMR
Research definitely points toward a reduction in BMR in response to a calorie deficit and fat loss. Here’s the thing though… when we lose weight, our energy expenditure is going to decrease with or without the starvation mode. A lower weight means less tissue to support, less mass to move around, etc.
The starvation mode comes into play when this drop in energy expenditure is greater than what would be predicted given the decrease in weight. It’s an overcompensation, if you will. This phenomenon is why someone who’s naturally 135 lbs will likely have a higher energy expenditure than someone who dieted down to 135 lbs from 200 lbs.
While the ‘buzz’ suggests there’s a specific calorie intake that triggers this reduction in BMR, there’s not a lot of truth to that. It’s really something that’s going to happen regardless of the size of the calorie intake or deficit. The driving factor seems to be fat mass. The more fat you lose, the greater the starvation response of BMR you’ll realize. Smaller deficits will merely decrease the rate at which you lose fat and thus slow down the metabolic adaptation. Both paths point to the same destination though.
Here’s the thing… the starvation mode does not completely shutdown your metabolism. If it did, you’d be dead! It merely drops your energy expenditure slightly. The largest recorded drop that I’m aware of was observed in Ancel Keys’ Minnesota Starvation Experiment.
This research placed relatively lean men on a 50% calorie deficit for 6 months. While there was a 40% drop in metabolic rate, roughly 2/3 of this was accounted for by the drop in body weight. In other words, the majority of the reduction in metabolic rate was expected given the smaller bodies.
That’s a 15% drop in metabolic rate due to the starvation response in lean men dieting for 6 straight months on 50% of their calorie needs. Their average ending body fat percentage was something around 5%.
Hardly anyone reading this is in this situation. Most of you likely have excess fat to lose and you’re not going to be eating such low calories for extended periods of time. When you have an abundance of fat and you’re not starving yourself, the starvation response is going to play a much smaller role in dropping BMR.
Keep in mind that this isn’t happening meal to meal or even week to week. This is a longer term phenomenon. In fact, some research suggests that metabolism increases with a day or two worth of fasting.
None of this implies that a calorie deficit will no longer work. Rather, this information implies that after you’ve lost a considerable amount of fat, your predicted maintenance might be inflated.
Plateaus
Believe it or not, but plateaus can and most definitely do occur for reasons besides the starvation mode.One of the key problems is the method by which people are identifying plateaus. Most people resort to the number on the scale. If it moves in the desired direction – VICTORY! If it doesn’t – FAIL! If the scale isn’t budging, they’re in a plateau. Pair this with the unrealistic expectations in terms of how quickly it should happen, and you have a recipe for a misidentified plateau.
Case in point, all kinds of crazy stuff can happen with glycogen and water weight when dieting and training. The scale’s measuring everything from muscle and fat to poop and water. Some of these variables can be rising while others are falling. It’d be nothing to retain 3 lbs of water while losing 1 lb of fat over the course of a week.
The shortsighted dieter who bases success or failure on the number portrayed on the scale would write this off as a flop. Tangentially, she’d probably get so stressed and frustrated that she’d binge the following week. This would be followed by feelings of guilt and she’d diet hard the following 2 weeks. At the end of the four weeks, she’d only remember the good weeks and think she “earned” a loss for the month. When the actual weight for the month is breakeven, she’d be flabbergasted and totally disregard the one full week of binging and the possibility of fat loss being masked by water storage or whatever.
See how destructive this mindset can be?
Plateaus do happen though. I’m not naive. In my experience, the most likely culprits are as follows…
Most commonly they’re caused by inaccurate calorie estimates. People tend to overestimate the energy they’re expending and/or they underestimate the calories they’re consuming. We discussed how to minimize this error in the calorie section above.
The lighter you are though, theoretically speaking, the less wiggle room you have for error. Suppose you’re 125 lbs. Your maintenance intake is likely 1,750. A reasonable deficit would be 25%, which would lead to a daily calorie goal of 1,300.
As there are 3,500 calories in each pound of fat, assuming you lost nothing but fat while dieting, the above deficit would lead to a 1 lb loss every 8 days or so.
Now what if this person was underestimating their intake by 5% or so (there’s research showing people underestimating by as much as hundreds and even thousands of calories) and overestimating their expenditure by 10% or so. This could add another 200 or so calories to their daily intake, thus reducing the actual daily deficit to 250 calories.
Using the same assumptions from above, the actual deficit would lead to a 1 lb loss every 14 days. I’m being conservative in this example and this person’s expectations would be off by as much as 50%.
In this case it’s not that you’re deficit isn’t working… rather it’s that you’re eating closer to maintenance than you realize.
Second, many people forget that as they get lighter and lighter, their initial calorie deficit becomes smaller and smaller. A very generic calculation for BMR, which is merely one component of energy expenditure, is 10 calories per pound of body weight.
If you were once 185 lbs, it’s likely that your BMR was close to 1,850 calories. If you’re now 135 lbs, it’s reasonable to assume that your BMR is in the neighborhood of 1,350 calories. If you never adjusted your calorie intake from then until now, it’s pretty easy to see how a plateau might arise. Eventually, if enough weight is lost, what was once a deficit can become maintenance.
The simple solution would be to adjust your calories downward at regular intervals as you lose weight – maybe every 10 lbs or so.
Third, I know it’s all the rave to suggest that you can’t gain muscle while being in a calorie deficit. And I get it… building muscle is a costly project and if you’re not eating enough to maintain the tissue you currently have, your body isn’t going to like adding a bunch of metabolically expensive tissue such as muscle. It makes a ton of sense on paper.
However, I’ve seen concurrent body composition changes enough times to know that it does happen. The more untrained and/or the fatter you are, the more likely this possibility seems to be. It’s not necessarily something you should expect. And if you’ve been training for a long time and you’re reasonably strong, it’s likely not going to happen to any significant degree.
But if you’re losing fat and you’re gaining muscle, the fat loss can be masked on the scale by the muscle gain.
Of course there are other possibilities. Maybe you’re on a medication that screws up your water balance or metabolism. Maybe you have a medical condition that causes metabolic rate to be depressed… something such as a thyroid problem. Maybe you are in fact experiencing the starvation response. Maybe you’re at a point where refeeds or some cyclical approach with carbs makes sense. Or maybe you simply need to give your body a break, bring calories up to maintenance, and rest for a couple of weeks.
[This is part 5 of 6. Please stay tuned for the next installment]
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