BMR and Muscle Mass:
Muscle tissue is metabolically, highly active even at rest, whereas fat tissue is not. Thus, lean body mass (LBM) greatly influences a body’s energy requirements and, in conjunction, its nutrient needs. An increase in muscle mass, for both males and females, will elevate BMR.
Starvation and Restrictive Dieting:
Metabolic rate can drop to as low as 20-30% during a period of starvation and restrictive low-calorie dieting. This drop is due to the body’s effort to conserve energy (and its eventual loss of lean tissue) by slowing its BMR. This slowing process is a natural protective mechanism that conserves fat stores when a food shortage occurs. Because of this, consumption of fewer calories than required to sustain BMR will be counterproductive, and can actually cause body fat levels to increase.
5. What impact does exercise have on BMR?
While we can’t change our genetics, age, gender, height or (in most cases) our environment, we can change our body composition. We can decrease our body fat and increase our lean body mass (LBM), which will mean a higher metabolic rate. Changing our body composition is done through proper diet and exercise — two things that will directly impact BMR.
Exercise can increase BMR and, depending on intensity and duration, the metabolic rate may remain elevated for several hours afterward. During sustained, large-muscle exercises like running and swimming, people can generate metabolic rates that are ten times higher than their resting values. Exercise will also increase your muscle mass, which will then increase your BMR.
This is why many top athletes can consume high amounts of calories and still maintain low body fat. The value of exercise cannot be overlooked — it is critical for both short and long-term weight loss; it prevents obesity, poor posture, muscle and bone loss, pre-mature aging, depression, and many other health issues, and it facilitates ultimate fitness levels; physically, mentally, and emotionally.
6. Calculating daily calories. Gender: why men can eat more than women and what women can do about it.
Whether you are interested in health, fitness or weight loss, calories should always be calculated according to your personal BMR, activity level and other variables. While gender is an influential factor for women, it is not necessarily the culprit when it comes to a lower BMR. Instead, a woman’s lower BMR is due to a smaller proportion of muscle mass to fat. That said, females should consume fewer calories than men (childhood, adolescence, pregnancy and athletes excluded). Girls, don’t despair; if you exercise you can eat more. Even though exercise in general increases BMR, strength training is the master to key to the development and protection of lean body mass, which as stated earlier, increases BMR, thus guaranteeing weight loss. However, there is a limit to how much muscle mass females can or want to have on our physique, so we as women have to deal with our limitations when it comes to calorie consumption.
Article comments
1 - Bob Lloyd
Although the intention of the article is very good, there are some glaring factual mistakes about the human body. I hope you don't mind me correcting them here.
[Protein is the "cellular building block" and is a main component of bones, muscles, organs, glands, cartilage, skin, and blood.]
This is misleading. A protein is just a string of amino acids, it's a biological chemical. They are found throughout the body and are no more a main component than water is. They are ubiquitous and provide a very wide range of functions but in essence, they are just chemicals. In the case of bone, the main component is not protein, but calcium phosphate, an inorganic chemical.
[Fats aid in heart and brain health, prevention of certain cancers, and help reduce other ailments like depression, inflammation, and blood pressure.]
Fats is a common term for lipids, a class of biochemical which includes steroid (as in hormones), phospholipids (as in cell wall proteins), many vitamins, and even polyketides.
Saying they help in heart and brain health is meaningless but saying they aid in prevention of certain cancers and reduce depression symptoms is positively misleading and shows a lack of understanding of the medical details. The implication is that you need them to stave off depression - which is nonsense. You need them to stay alive.
The fact is that foodstuffs are digested, that fats, proteins, and carbohydrates, are metabolised into simpler chemicals which are then used to synthesise a wide range of complex biological molecules. These biological molecules are ubiquitous, all around the body, and they can't be associated with specific functions in the way you describe.
Proteins for example include hormones (chemical messengers), structural components (such as collagen), enzymes (such as pepsin), carriers (such as haemoglobin), and so on. Proteins perform a diverse range of functions throughout the whole body.
The same could be said of the metabolic products of fats and carbohydrates. It's simply incorrect to say that "Not all calories are created equal". Calorie is a measure of energy and the body doesn't care what the source of the energy is. Once it's metabolised and the energy is absorbed into the bonds of ATP (Adenosine Triphosphate, the main energy storage and transport mechanism of the body), all calories are identical.
I appreciate your intention to get people to be sensible about this stuff, but it is really important to get the biological details right. The whole detox industry seems intent on spreading confusion and misunderstanding so it's important that people don't get the wrong idea about things like carbohydrates, fats and proteins, and their role in human biology.
2 - Christine
Bob: thanks for your insight and I was trying to speak so that the average person could understand. Will recheck later.