Tag Archives: Body Mass Index
Training on an empty stomach for weight loss
(12-14-2014) To succesfully lose weight
the combination of a healthy diet with caloric restriction combined with training is more effective than using a diet or training alone. The last few years quite some research has been performed on endurance training on an empty stomach. These studies showed that fat metabolism was increased directly after fasted exercise compared with regular fed exercise. In addition fasted exercise improved insulin sensitivity and lead to a better glucose tolerance. These adaptations should in theory help weight and fat loss. To test this hypothesis, scientists performed a study to answer whether training on an empty stomach is more effective for weight loss.
Weight loss or improving body composition?
Many people wanting to improve their looks or their health seek to lose weight achieve this goal by dieting, a dedicated training plan or both. Often they set goals to lose a certain amount of weight. Others don’t use the scale to measure their progress, but look towards body fat calipers or other methods to assess their body composition. So the important question is: Which is better focussing on weight loss or improving body composition?
The advantage of setting a weight loss goal is that it is easy to measure weight. However, the weight lost can be caused by loss of fat mass, muscle mass, water or a combination of these. Measuring body composition allows to keep track of changes in the relative amount of fat during diets and weight loss training programs. Changes in body fat percentage better represent changes in someone’s health and fitness. As stated above, weight loss can also be caused by a loss of muscle tissue. This not only makes a person weaker and less fit, resting metabolism decreases as well. This makes retaining weight loss much harder.
Consider the following example:
Subject 1 and Subject 2 before weight loss:
| Table 1 | Subject 1 and Subject 2 |
| Age | 25 years |
| Length | 182cm/6′ |
| Weight | 90kg/200lbs |
| BMI | 27.2 (overweight) |
| Fat Percentage | 25% |
| Fat Mass | 22,5kg/50lbs |
| Fat Free Mass | 67,5kg/150lbs |
Subject 1 and Subject 2 followed different weight loss programs and the results are:
| Table 2 | Subject 1 | Subject 2 |
| Weight | 82kg/182lbs (-8kg/-17.8lbs) | 88kg/196lbs (-2kg/-4.4lbs) |
| BMI | 24.8 (Healthy) | 26.6 (Overweight) |
| Fat Percentage | 23% (-2%) (Overweight) | 18% (-7%) (Healthy) |
| Fat Mass | 18.9kg/42lbs (-3.6kg/8lbs) | 15.8kg/35.1lbs (-6.7kg/14.9lbs) |
| Fat Free Mass | 63.1kg/140.2lbs (-4,4kg/9.8lbs) | 72.1kg/160.2lbs (+4.7kg/10.4lbs) |
In this example we can see several interesting things. First, Subject 1 lost more weight in total and therefore was no longer overweight according to the BMI. However, his fat percentage did not decrease as much and he is still considered overweight in this respect. This means that, although he did manage to lose some body fat, most of the lost weight was not fat, but muscles and water instead.
Subject 2 on the other hand did not lose as much weight, but did manage to bring down his fat percentage by a considerable amount. Enough to be classified as healthy when looking at fat percentage. The BMI in contrast, which depends only on weight and length, still classifies him as being overweight, even though the health risk as a result of too much fat has decreased considerably. Subject 2 managed to lose a lot of fat and actually gain some muscle mass. Not only does this make him look a lot better than Subject 1, he is healthier as well.
This example serves to illustrate that it is better to improve body composition, than to just focus on losing weight. Someone who gains muscle mass and burns fat mass at the same time, will look healthier and lighter than they actually are. Muscle tissue density is much higher than fat tissue density, meaning that in the example above Subject 2 looks a lot slimmer than Subject 1 despite being heavier.
See also:
-Is Cardio Training the Best Way to Lose Weight?
Waist Circumference
Waist circumference is a measurement that gives an indication of fat related health risk. Although your body composition is an important indication as well. Not everyone has access to a reliable device to measure body composition such as an MRI-scan or DEXA scan or to someone skilled with a skin fold caliper. To measure waist circumference only a flexible measurement tape is needed so it is accessible to practically everyone and not complicated. In addition, body fat is not distributed in the same way for everyone. Two persons with the same relative amount of body fat can store their fat on different locations such as hips or inside the abdomen. Since internal abdominal fat (see also visceral fat) greatly increases risk of developing cardiovascular disease and diabetes mellitus type 2 and more visceral fat corresponds with an increased waistline, this measurement can help indicate whether or not you are at increased risk for developing these disorders.
How to measure waist circumference
Take a flexible measurement tape and put it around your waist. The tape measure should be held above the navel but below the lowest ribs at the narrowest point of the torso. Make sure the tape measure is completely horizontal and that the one who is measured stands upright and relaxed and before measurement breathes out normally. Compare the value with those in Table 1 below to get an indication of developing cardiovascular disease or other fat related conditions.
| Waist circumference norms (in centimetres and inches) | ||
| Men | Women | Risk category |
| Less than 94cm (37 inch) | Less than 80cm (inch) | Low |
| 94-102cm (37-40 inch) | 80-88cm ( inch) | High |
| Greater than 102cm (40 inch) | Greater than 88cm ( inch) | Very high |
Table 1: Waist circumference norms
Note: these norms apply to Caucasian adults and Asian women. Currently not enough data on other ethnic groups is available.
Risk category:
Low: You are not at increased risk of developing lifestyle related diseases such as cardiovascular disease. You can maintain your current lifestyle, although it does not hurt to improve it further.
High: You are at increased risk of developing cardiovascular disease or other lifestyle related diseases. Either improving your diet, decreasing your energy intake or starting strength and endurance training will help losing weight and abdominal fat.
Very high: You are at very high risk of developing lifestyle related diseases. Large changes in lifestyle in multiple areas are necessary to improve your health. Improve your diet, decrease your energy intake, start training to increase muscle mass and improve cardiovascular endurance and exercise more every day.
References:
-Bushman, B. (2011). Assesing Personal Fitness. Complete Guide to Fitness & Health. First Edition. USA Human Kinetics.
-Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. 2007.
BMI
The Body Mass Index (BMI) is a measure which gives an indication whether someone has a healthy bodyweight, underweight, overweight or obese. The BMI can be calculated with the following formulae:
The number that is calculated from one of these formulae can be looked up in the table below and determines if someone has a healthy weight or is nderweight, overweight or even obese.