Understanding Metabolism

Keshav Kumar
Every time one hears of dieting to lose body weight the concept of metabolism surfaces especially phrases such as “increasing metabolism” or “increasing metabolic rate”, etc. For those who are unaware about what this means or its relevance with weight loss may find it exciting or even intimidating at times to having been given the secret power to change alter their metabolic rate by following a unbalanced, low calorie, nutrient deficient, and bland weight loss diet.
Most people dieting to lose weight coupled with being less aware about what metabolism is may end up with a altered metabolic rate, physiological and psychological response than may potentially take them further away from their fitness goals.
Metabolism is the “sum total of all reactions taking place within the body geared towards building it up and breaking it down”. Building up functions are based on anabolism (anabolic functions) while breaking down functions are based on catabolism (catabolic functions). While this is a scientific definition of metabolism, lets look at a few terms that are commonly misunderstood and their respective definitions/meaning and relevance for a fitness goal (eg. weight loss).
Thermic Effect of Feeding: All foods we eat have some effect on our metabolism; while some increase it more others do so to a lesser extent. TEF looks into this aspect and signifies the energy utilization during digestion and absorption of consumed food. The contribution of TEF is as low as 10% of the total energy expenditure.
Physical Activity or exercise is also very important. It is the activity performed as part of a planned exercise program or for those who are in to sports can be considered as the energy expenditure for a particular sport. This is one component which can be highly variable between individuals as different people would be performing different activities as part of their workout and that too at different intensities. High intensity activities usually can create a demand for energy not only during the activity but afterwards as well in comparison to low intensity activities thereby further impacting metabolism by increasing it.
Non-Exercise Activity Thermogenesis: Non-Exercise Activity Thermogenesis or NEAT is a summation of all activities performed as part of living other than the regular exercise. Examples: taking stairs in the office instead of elevator, moving around the house/office, playing with children, preparing food, etc. It is not as big a contributor to energy expenditure as the exercise activity as such but still does play a significant part. Solely considering only this parameter may not be enough and as such is integrated as part of a fitness program.
The Total Daily Energy Expenditure (in other words the metabolic rate) is usually determined as a sum total of RMR (this includes BMR), Physical Activity (exercise and NEAT) and TEF.
Now that we have a basic understanding of metabolism, metabolic rate and parameters on which metabolism is dependent on, let’s address some common misconceptions:
Eating smaller meals frequently increases metabolism thus leading to weight loss.
Based on the TEF, we know that foods such as protein can increase metabolic rate to a significant degree. However, keep in mind that a higher metabolic rate also means an increased demand for energy in the form of food. Thus, a higher metabolic rate corresponds to consuming more calories than the recommended caloric intake. If aiming for weight loss, it is assumed that total calories are going to reduce over a period of time, irrespective of whether two big meals are consumed in a day or six small meals. This would mean that as calories keep going down after a certain point, metabolic rate is also going to reduce. In simple words, Higher Metabolic Rate = More Food. For losing weight the focus should not be on increasing or decreasing metabolic rate, but rather on consuming calories that are relevant to one’s individual calorie requirements for weight loss. Metabolism will vary for everyone and that is why there is no one specific value for it.
Eating less food is the only way to lose weight.
While it is true that maintaining a calorie deficit for a predetermined period of time is enough for weight loss, it is also true that this calorie deficit (taking in less food) is also going to impact metabolism by reducing the metabolic rate. Some folks just focus on this one aspect and keep on reducing food intake which results in them having altered their metabolism to a lower level which may impact their overall health and not just their fitness goals in a negative way. Another way to lose weight is also to, include workouts such as strength training and cardio to achieve weight loss. Consider the following example:
An individual with a weight maintenance daily calorie intake of 2000 kcal who is not doing any type of exercise would have to reduce his/her intake to say 1500 kcal to lose 1 pound (0.5 kg) of fat each week. Now if the same individual starts doing strength training and cardio 3 – 5 times per week, with say 3 days devoted to strength exercises and 2 days of cardio, his/her daily calorie intake may rise to 2500 kcal to accommodate for the increased energy expenditure and their new weight loss based daily calorie intake would now be higher (than previous) at 2000 kcal to lose 1 pound (0.5 kg) of fat each week. Now, losing fat at 2000 kcal is going to be much better in comparison to losing fat at 1500 kcals. Of course, this is just an example and not true calorie numbers.
Protein increases metabolic rate, so let’s eat protein only.
Eating only one type of food will provide only one type of nutrient profile to the body, thus making it deficient in other nutrients. Carbohydrates and fats are also important to the body and have their respective functions to perform at a cellular level thus maintaining overall health and fitness. A lot of nutrients such as Vitamins A,D,E,K need fat to be utilized within the body. Similarly, carbohydrates and fats also regulate various neurotransmitters and hormones to maintain psychological and physiological functionality. Eating a well balanced diet comprising of protein, carbohydrates, fats, fiber, vitamins, minerals and even adequate water consumption is better than consuming only one type of food group. Before following any random type of diet, exercise and supplementation program it is best to consult with a qualified doctor.
(The writer is a fitness consultant and can be reached at seventeenk 86@gmail.com)