What are your choices for weight loss? The conventional wisdom is “eat less and move more”.
This sounds intuitive, but how much truth is there?
Weight loss is like driving a fast car down the motorway. If you do not check your mirrors and the blind spot before changing lane, you crash sooner or later.
In practice, we are all bombarded daily by different advertising campaigns maximising profit and emphasising inconsistent messages. It is impossible to know which mirror to look into and where your blind spot might be unless you are a scientist or clinician who actively work in this area. I am fed up with this situation and that's part of the reason why I spent 2.5 years building PhD Fitness.
Attempting different fad diets is like changing lanes without looking while cruising at 70mph. Pure madness!
Time to come to senses. Your body maintains the balance between Energy Intake (EI) and Total Energy Expenditure (TEE) (Figure 1). Surplus energy (when EI > TEE) is stored as glycogen and fat, and energy deficit (when EI < TEE) is met by burning them. Temporary energy deficit is met by primarily burning glycogen. This can mount to about 1kg initial body weight loss for a 70kg adult, as you lose the water associate with glycogen at the same time. Long term energy deficit burns fat. The important questions to answer are
A) How do I create a sustainable long-term energy deficit to lose fat?
B) How do I keep the weight off after weight loss is over?
For these, you need to know TEE better. You spend energy in 4 different ways: physical activity, digestion aka thermic effect of food (TEF, accounting for ~10% of total energy expenditure), obligatory energy expenditure (maintaining essential organ functions), and adaptive thermogenesis (Figure 2). Only physical activity might be in your control. The other 3 are not. Needless to say, it is important to be mindful of the factors out of your control.
TEF varies depending on food. It does not appear to be key to your weight loss success so far.
The obligatory energy expenditure maintains the essential organ functions. Lean mass burns as much as 7 times of energy maintaining the same amount of fat mass. Easy to see it helps to have a lean body if the goal is to increase TEE. We will come back to this in another post.
Adaptive thermogenesis (AT) is a variable amount of heat generation depending on how much you eat and the environment. When you eat more, you produce more heat and feel warm. When you are starved, your produce less heat and feel cold.
As you may have guessed, adaptive thermogenesis reduces weight changes, be it weight gain when food intake is plentiful or weight loss when you are not eating much. This strategy makes sense for evolutionary selection - a caveman probably wanted to save energy when food was hard to find.
Consequently, hunger strike is unlikely to help you achieve your weight loss goal. It is not sustainable and once you come off the diet, your body weight will come back or worse overshoot. This is the blind spot you need to look at before manoeuvre. In fact, eat a little bit less and move a lot more at the same time is the most effective strategy for weight loss. This is supported by the analysis of 30 different weight loss clinical trials of lifestyle-based interventions [1].
Adaptive thermogenesis might still sound mythical to you. I will write another post to help you understand it a lot better next week.
PhD Fitness (phd-fitness.com) uses a clinically-validated model to predict body weight changes considering all 4 types of energy expenditure. This helps you remove the guess work as to what/how much you need to eat and what type of physical activity you need to take for how long to achieve what weight loss goal in what time. The scientific goal setting helps set you off to a great start.
It takes about 10 seconds to register and your data are entirely private. Feel free to give it a try.
I’d like to have any comment you may have so that it can be developed into an app/website that will best help you achieve your goal.
1. Greaves CJ, et al. Systematic review of reviews of intervention components associated with increased effectiveness in dietary and physical activity interventions. BMC Public Health. (2011) 11:119.