walking to lose

Question
Hi Robert, I'm trying to drop some weight. I know about diet and I'm wondering how much my walking 3 miles per day 3.7-->4.0 mph will add to my goal. I have a descent sweat happening when I'm finished.  I'm 59 yrs, 5'8", 175.
How much more would I help myself if the 3 miles included 5 to 10 minutes of jogging at 5-->5.5 mph?
Thanks for your time.
Ken

Answer
First of all, let's look at your goals.  Based on your height and weight, your body mass index (BMI) is 26.6.  The bad news is that this puts you into the overweight category (Normal is 18.5 to 24.9; Overweight is 25 to 29.9).  The good news is that you are only slightly over the 25 point mark, and you don't have as much work to do as you would if you were very overweight.

BMI only takes into account height and weight.  It does not take into account percentage body fat.  At your age, you are likely developing a condition called sarcopenia.  Sarcopenia refers to the age-related loss of lean skeletal muscle mass, and happens to everyone as they get older.  It can, however, be greatly reduced though certain types of exercise.  The reason to mention sarcopenia with respect to the BMI is because it can mask your overall fitness level.  For example, you might have the same weight as a 25 year old of equal height.  However, the 25 year old would likely have a higher percentage of muscle.  And of course if he has more muscle yet weighs the same as you, he must have less of something else: body fat.

Assuming you are of average build, let's target a BMI of 22 as your goal.  At your height, you would need to weigh 145 lbs to have a BMI of 22.  (You can compute your BMI for free on many web sites.)  This corresponds to a weight loss of 175 - 145 = 30 lbs.  Your goal should therefore be to lose 30 lbs of fat.  Ideally, you do not want to lose ANY muscle.  If possible, you would actually like to gain muscle.  For example, you might wind up losing 40 lbs of fat, yet gain 10 pounds of muscle.  Your net weight loss would still be 30, but you would be much healthier than if you just lost fat.

You said that you know about diet.  Have you computed your total daily energy expenditure (TDEE)?  This number is based on your age, gender, height, weight, and activity level.  (You can also compute your TDEE for free on many web sites.)  If the only activity you do is walk 3 miles every day, I would rate your exercise level as "moderate".  Putting in all of your stats and a moderate exercise level, your TDEE computes to 2,500 calories.  This value represents the number of calories you need to eat every day to maintain your current weight.

In order to lose weight, you would need to eat fewer calories than this.  The best plan is to reduce your TDEE by 20%.  (Never reduce it by more, or you will risk losing lean muscle in addition to body fat - a very bad thing to do!)  Reducing your TDEE by 20% gives you a target value of 2,000 calories.  If you eat 2,000 calories and keep up with your daily exercise, your caloric deficit will be 500 calories per day.  In general, it takes a caloric deficit of 3500 calories to lose 1 pound of fat, so :

3,500 / 500 = 7.0

In other words, on this diet you will lose 1 lb of fat every 7.0 days (1 week).  This is a very reasonable diet and falls within healthy weight loss rates.

Now, I know this has been very long and complicated, but it has been necessary in order to provide a scientific answer to your question based on sound science.  Your question basically asks how much more will doing the additional jogging help you in your goals.  The answer can be determined by recognizing that your jogging will serve to raise your TDEE activity level slightly.  The TDEE activity level essentially acts as multiplier in the overall calculations.  Online TDEE calculators usually only give you 4 or 5 choices for activity level, such as "sedentary", "light", "moderate", etc.  The 5 to 10 minutes of jogging every day is not going to boost your activity level to the next level ("heavy"), however, it will raise it slightly.

I am familiar with the TDEE formulas, and I would estimate that this additional amount running will raise your use your TDEE activity level multiplier to around 1.625 (a value between "moderate" and "heavy" - but closer to "moderate").  This revised activity level generates a new TDEE of 2,651 : 101 calories more than before.  Your new daily caloric deficit would be 601, and your new weight loss rate will be:

3,500 / 601 = 5.8

So with the extra running, it will only take you 5.8 days to lose a pound of fat, as opposed to  7.0 days.  This may not sound like much, but it is 17.1% faster.

Let's look at your long term goal of losing 30 lbs of fat.  At the lower weight loss rate, this will take you:

30 * 3,500 / 500 = 210 days (30 weeks, around 7.0 months)

At the higher weight loss rate:

30 * 3,500 / 601 = 174 days (25.0 weeks, around 5.8 months)

So you would reach your goal 1.2 months ahead of time if you include running in your daily routine!

Keep in mind that all of this is predicated on you sticking to your diet.  If you eat 1 large cookie every day, this might add an additional 100 calories, which would wipe out the effects of the additional jogging.  I always recommend that people starting a diet program purchase a small food scale and journal, and then keep daily food logs of everything they eat.  This is the only way to know for sure if you are on target.  Most people have little concept of the caloric content of their food, and mis-guess portion sizes.  If you start measuring and recording everything you eat, you will eventually learn what are appropriate amounts and types of foods.  After a few months, you probably won't need to weight and record everything - you will have a good feel for what is appropriate to eat all on your own.

Good luck.