You want to lose weight. Now what?

Well, if you are like most people, you start going to the gym, throw out (or eat your way through) any remaining “junk” food, browse the latest weight loss fads until you find one that resonates with you, fill your cupboards and fridge with healthy foods prescribed by your new diet plan, and wait for the pounds to fall off.

But they don’t.

Despite changing your eating habits and exercising daily, the scale has barely moved in 1 week. You’re angry, disappointed, exasperated, and overwhelmed. Maybe you think “What’s the point?” and proceed to cancel your gym membership and binge on your favourite comfort foods that you swore off only a short time ago.

This scenario is very common among my clients who come to me seeking weight loss support. They can’t understand why they aren’t losing weight despite their best efforts. When I gently tell my clients that they likely were losing weight, but just couldn’t see it, I’m usually greeted with a look of skepticism and bewilderment. “But the scale didn’t show me I was losing weight!” they respond. To which I reply, “The scale does a bad job of measuring weight loss.” More blank stares.

Here’s the thing, the physiology of weight loss and gain is incredibly complicated and goes far beyond the “move more and eat less” dogma. In fact, despite all the research that has gone into understanding weight loss and gain, scientists still don’t fully understand what makes some people better able than others to lose and maintain weight. However, what we do know is that weight loss happens week-to-week, rather than day-to-day, which makes your scale a very poor barometer of weight loss and gain.

When you step on the scale, you are measuring much more than fat mass. Most of the time, you are measuring shifts in fluid. Time of day, food intake, medical conditions, and activity status can all influence our water weight, as can normal physiological processes including sweating, urinating, defecating, and digestion. (To exemplify just how significantly our weight can fluctuate day-to-day, I will be writing a follow-up blog post to share my weight experiment.)

So this leads us to an important question: What is a realistic weight loss approach and how do we know if we are losing weight?

To answer this question, we need to consider the following:

Our basal or resting metabolic rate

We must eat a certain number of calories each day to support normal organ function and maintain our current size. This number is referred to as our basal or resting metabolic rate and can either be measured (which is usually quite pricey) or estimated from an equation (see below). Our age, gender, size, and body composition all influence how much we need to eat to meet our basal needs. One common myth is that larger body sizes have slower metabolisms. But the reverse is actually true (provided there is no underlying medical condition); a smaller body size means there is less of you and as such, you need fewer calories to support your basal needs. It is for this reason that weight loss results in a similar or slower metabolic rate. Using myself as an example, my measured metabolic rate is 1450 calories. This is fairly consistent with my predicted metabolic rate of about ~1350. (Note: measured metabolic rate should always be used before predicted metabolic rate.)

Mifflin-St. Jeor Equation

Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5

Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161.

Our activity level

Ultimate playoffs 2017

Because we don’t spend our day lying quietly in a bed, we need to add in calories or food energy to meet activities of daily living, as well as structured exercise. This is usually calculated by multiplying your basal or resting metabolic rate by an activity factor. Below you can see what the activity factors are, along with their qualifiers.

1450 x 1.5 = 2175 or 2200 calories.

This is how much, on average, I need to eat each day to support normal physiological functions, sustain my current body size, and ensure I have the fuel I need for my level of physical activity.

Activity Factors

1.2 if sedentary, little or no exercise and desk job

1.375 if lightly Active, light exercise, or sports 1-3 days a week

1.55 if moderately active, moderate exercise, or sports 3-5 days a week

1.725 if very active, hard exercise, or sports 6-7 days a week

1.9 if extremely active, hard daily exercise or sports and physical job

Calorie requirements for weight loss

Here is where I often lose people, so stay with me. 🙂

1 pound of body weight = 3500 calories. So, if you were trying to lose one pound per day, you would need to reduce your total calorie intake by 3500. You can see the logistical issue here as most of us are not eating enough to lose 1 lb of weight per day. Rather, standard guidelines suggest reducing your calorie intake by 500-1000 calories per day, which would translate to a 1-2 lb weight loss per week (7 days x 500 calories = 3500 or 1 lb of weight loss and 7 days x 1000 calories = 7000 or 2 lbs of weight loss). Using my example: 2200 – 500-1000 = 1700-1200 calories per day for weight loss.

Now perhaps you are thinking that you will just reduce your calories further to lose weight more quickly. This is NOT recommended for the following reasons:

  • Few people can be satisfied eating fewer than 1200 calories (or even at 1200 calories, for that matter)
  • Over-restricting your diet can lead to disordered eating symptoms.
  • Eating less than your metabolic rate can cause your body to go into starvation mode, where it lowers your metabolic rate and does everything it can to stop you from losing weight.

Of course, you can enhance your rate of weight loss (slightly) by engaging in physical activity. However, keep in mind that it is a lot easier to eat 100 fewer calories than it is to burn off 100 calories. So, how do you know you are losing weight? By focusing on your behaviour and NOT the scale. I recommend tracking your diet using an app such as CRON-O-Meter. This app allows you to see your daily and weekly calorie intake, your macronutrient distribution, as well as your vitamin and mineral intake. Tracking your diet can help ensure you are eating enough, keeps you accountable, and is useful for identifying challenge areas.

Scales can be helpful to note your overall trend, but I don’t recommend weighing yourself more than every 7-14 days, given the number of factors that influence your daily weight. When you do weigh yourself, take your weight in the morning, without clothes, while fasted, and after voiding. Finally, it’s important to remember that weight loss is an outcome of behaviour change. It’s hard to influence the outcome without first changing the process!

Full disclosure: Susan Macfarlane Nutrition provides consulting services to the company, CRON-O-Meter.