Most people have the general premise down. If you want to lose weight, you need to burn more calories than you eat. Calories in vs. calories out. While I certainly don’t base my meal plans on this idea alone, this statement holds true. So, a person looking to lose weight, often in an attempt to see results quickly, will dive head first into a plan that involves slashing calories drastically, while simultaneously amping up their time at the gym. Initially, they see results. Then, usually pretty quickly, they just stop losing. How can this be? They MUST be burning more than they’re eating! Usually this leads to further cutting calories to no, or little, avail. What is going on?
They’re not eating enough.
When you cut your calories too low, you basically lower your resting metabolic rate (RMR), making your body burn calories much slower than previously. This is exactly what you do NOT want, when the goal is weight loss. Your body requires a certain amount of calories just to exist. If you were to lie in bed all day and do nothing, you would still burn a significant amount of calories breathing, perspiring, digesting, etc. Add to the the activities of day to day living AND exercise, and you’re burning much more.
By cutting your calories too low you:
*Decrease your muscle mass: All weight loss is not equal! When losing weight, you can expect to lose some muscle, but you want to keep that to a minimum. When you’re not eating enough, your body often catabolizes more muscle tissue for energy, which will still result in a loss on the scale, but it will not get you closer to the body you’re trying to achieve.
*Lower Testosterone: Yes, both men and women produce testosterone, women just produce much less. Testosterone is a steroidal hormone which helps build and maintain muscle mass (among other things). A decrease in testosterone leads to a decrease in muscle mass, and a decrease in muscle mass results in a lower metabolism, because muscle burns calories.
*Decreased Leptin: Leptin is an important hormone for regulating metabolism and appetite. Basically, leptin is a hormone that needs to be a certain level to signal to your brain that you have sufficient energy. As leptin levels drop, your brain gets signaled that you do NOT have enough energy to perform certain tasks, and goes into a kind of “starvation mode”, thus slowing metabolism.
*Decreased Thyroid Production: Thyroid hormone controls a LOT of bodily functions. It regulates your metabolic rate, and protein, carb and fat metabolism. Thyroid hormone goes down, metabolism goes down, plain and simple.
*Loss of energy: A degree of tiredness is expected during a weight loss period. You’re putting your body under stress that it’s not used to. However, extreme sluggishness is not a good sign. It is a very unpleasant symptom of a decreased metabolism. Consider prolonged energy loss as a sign that something is wrong.
In order to lose a healthy amount of weight, you should aim to eat between 500-1000 calories less than you burn per day. This equates to a 1-2 pound per week loss. The exceptions to this would be the first week on a weight loss program where you generally lose more than that (much of this is water) and it stabilizes out after that. The other exception is if you are very overweight to start with. In general, the more weight you have to lose, the faster you can safely lose it (I’m not talking about The Biggest Loser 20 pounds a week or anything, but up to 5 pounds a week is not that uncommon, depending on the person’s size).
So how much should you be eating a day? There are lots of calculators online for this, and although, many of them are slightly different, they are a good place to start. It’s always better to err on the high side and come down, because once that metabolism is slowed down, it can take a little bit to increase again (and usually there is weight GAIN while you do it). Experiment with the numbers, but as a general rule, men should not drop below 1500 and women should not drop below 1200 calories a day (and I happen to think this is still VERY low). I sometimes use a Body Media Link device to track how much I am actually burning throughout the day and I find it to be quite accurate. They are a little pricey, and there is a monthly fee for the site, but I find it very valuable for both myself and clients. If you would like to calculate your caloric needs yourself, here is the formula I use. (If you have more muscle than the average person, this will be lower than your actual needs, so bear that in mind.)
H=Height in cm
W=Weight in kg
A=Age in years
men: (10 x W)+(6.25 x H)-(5-a)+5 = RMR
women: (10 x W) + (6.25 x H) – (5 – a)-161= RMR
Now, take your RMR and multiply it by:
1.2 Sedentary: little or no exercise.
1.375 Lightly Active: light exercise 1-3 times per week.
1.55 Moderately Active: Moderate exercise 3-5 times per week.
1.725 Very Active: Hard exercise 6-7 times per week.
1.9 Extremely Active: hard exercise daily + a physical job.
This number will give you a rough number of how many calories you currently burn per day (your Total Daily Energy Expenditure, or TDEE). To safely lose weight, you can eat 500-1000 calories less than your TDEE (NEVER dropping below your RMR), or add more exercise, or better yet, a combination of the two! (For example, to lose a pound a week, eat 250 calories less than your TDEE, and exercise 250 calories more per day).
I hope this helps demystify some weight loss faux pas, and gets you closer to your goal. As always, feel free to drop a line with any questions!