One size (diet) does not fit all!

So here we are in January. Your New Year’s resolutions are still all fresh and shiny, and chances are good you’ve already started trying to shed a few pounds or exercise more or eat your vegetables like Mom told you.

If you’re dieting, you’ve probably adopted a plan described in a magazine article or a diet book. It might look like a good food plan—but how can you know whether it provides enough calories?

Here’s how to figure that out—and why it’s so important.

Many diet plans for women recommend somewhere between 1,000 and 1,300 calories a day, and that simply isn’t enough energy for you to exercise, protect your lean muscle tissue, and stave off hunger. That is, unless you’re a very small person or have a slow metabolism.

Maybe you’re thinking, But I’m in a hurry to shed this fat—so if I cut more calories, I can get lean faster.

I understand that you’re hot to fit into your skinny jeans, but cutting calories too severely is likely to backfire. Why?

• You’re going to feel more hungry and deprived—and thus are more likely to cheat.
• You’ll burn not just fat but also lean muscle, the engine that drives your metabolic rate and helps you burn more calories all day long.
• Your levels of the appetite-regulating hormones leptin and ghrelin will get out of whack, causing an increase in hunger. And who wants to end up after a diet with less muscle, more hunger, and a slower metabolism?

Have I gotten your attention? Good. Now I’m going to explain a better, smarter way than following a “one size fits all” diet plan.

You can’t preserve your hard-won muscles if you don’t get enough calories. Source: iStockphoto.com

Gathering information

Using a quick online calculator, you can get a fast and fairly accurate assessment of your total daily energy expenditure (TDEE). That’s the sum of the calories you burn just existing (basal metabolic rate) and through physical activity.

You can find one here. It’s free, fast, and super-easy to use.

The calculator will ask for your height, weight, age, and sex. It’s also going to ask you to choose an activity level, from sedentary through extremely active. The activity levels are defined as follows:

• Sedentary—person doesn’t exercise at all
• Lightly active—person does light activity or sports one to three times weekly
• Moderately active—person does moderate activity or sports three to five days a week
• Very active—person does hard exercise or sports six or seven days a week
• Extremely active—person trains intensely more than once a day or performs a job that is very physical

Once you plug in those numbers and select an activity level, you’ll get an instant estimate of “average actual metabolism” (your TDEE) and resting metabolism (the number of calories you’d burn if you performed no activity at all).

Yes, there is individual variation: some people require more energy (calories) than the estimate; some need less. But the number gives you a good place to start. You can always adjust as needed if you discover that you seem to burn more or fewer calories.

Figuring out how many calories to consume 

Now that you’ve got your estimate, you can make a smart decision about how many calories to cut.

The most sensible strategy is to reduce calories by a specific percentage: 15 to 20 percent for a moderate pace of fat loss, 25 to 30 percent if you want to be more aggressive.

You can safely be more aggressive if you have a lot of fat to lose and do not have a history of losing, then regaining weight.

If you’re smaller (and have 20 pounds or less to shed) or have been on and off diets for years, the more conservative approach is preferable.

Grab a calculator, and let’s figure this out.

The “average actual metabolism” (TDEE) number you determined above is your maintenance level—the number of calories it takes to keep your weight steady. Decide which percentage of calorie restriction you want to use: 15, 20, 25, or 30 percent.

Multiply TDEE by the percentage. If, for example, your TDEE is 2,200 and you want to cut calories by 25 percent, that’s 2,200 x .25, and the result is 550. That’s the number of calories to cut from your daily intake.

Subtract that result from TDEE to get the number of calories to eat daily while on your diet. In this example, that’s a TDEE of 2,200 – 550, which equals 1,650. At that rate, you should burn a pound of fat about every 6.4 days (subject to individual variation).

If you want to lose fat more quickly, consider increasing your activity level rather than cutting back on food.

Make sense?

Does this sound like a whole lot more food than a lot of diets permit? And, um, do you think it might be easier to stick to than that 1,000-calorie-a-day plan in your women’s magazine?

Please share your thoughts and experiences in the comment box. Let me know how your diet’s going!