Most people spend too much time trying to figure out how many calories they should be eating to lose weight, or how many grams of protein they need, or which foods they think they should avoid.
The reality is that your path is what matters, not your starting point.
Knowing how to adjust your diet based on your progress is far more important than figuring out exactly how to set it up at the start.
That's why you need a proper framework for your decisions before you try to change anything.
I've spent years collecting and analysing weight data from my clients to build my framework.
Here you're going to learn three principles I've distilled from that data. These principles help you visualise your progress and make accurate judgements that are independent of how you feel.
Most importantly they will help you take action.
Take daily weight measurements, but filter out the noise
The scale does weird things when you diet. You'll wake up one day looking like you've lost fat but the scale says you're stuck at the same weight as the day before. It'll say that you're heavier even though you know you've been doing everything right.
Here are some factors that affect your weight and have nothing to do with how well you stick to your diet:
- When you last went to the bathroom.
- How much food is in your digestive system.
- The amount of sodium in your food.
- How much water you drink.
- The amount of carbohydrates you consume.
Your weight data is noisy and you are looking for the signal.
On top of the noise there's observation error every time you take a measurement, even if you check the scale consistently at the same time of day and in the same state.
Track your weight daily and you don't have to worry about this.
That sounds counterintuitive, right?
Imagine your weight as a signal, varying continuously over time. Every time you step on the scale you're taking a sample, converting that continous signal into a discrete one.
In the same way that streaming music services compress audio by sampling it, you're compressing your weight data into a format that's more manageable.
If you don't take enough samples, you lose important information. A result from signal processing (called the Nyquist-Shannon theorem) suggests that you should use a sample rate greater than two measurements per week (a sample rate > 2/7) to attempt to reconstruct what's happening over the weekly timescale.
Example. Here are two curves showing weight gain in red and weight loss in green.
Both curves look the same if you sample at two points and try to extrapolate the trend line in black.
With daily weight measurements you have enough samples, all that's left to do is handle the noise.
You can filter out the noise by taking a moving average of your daily weight measurements. A simple type of moving average you can use is the arithmetic mean of your past weight measurements. I recommend using the last 7-14 days of weight data.
Example. Suppose you want to take a 3-day moving average and your last 3 weight measurements were 81kg, 80.7kg, and 81.3kg. Then your moving average is (81 + 80.7 + 81.3)/3 = 81kg, which you can use as a prediction for your next weight measurement.
Here's a comparison of real weight measurement data in black plotted against the moving average in red.
Notice how much easier it is to spot the trend by looking at the moving average?
Think of it as sliding along your weight data, smoothing out all the bumps and dips.
What you did last week predicts your progress this week
The moving average has many applications, in finance it's often used to generate trading signals for stocks. Here you are using it to support decision making and predict your future weight.
The accuracy of your predictions can be improved using machine learning techniques like regression. Regression algorithms try to model a relationship between an independent variable (like time) and a dependent variable (like weight).
Here is the output of a model I fitted to real weight data using ridge regression with the scikitlearn library in Python, the predictions from the model are in green and the actual values are in blue.
Notice how close the predicted values are to the actual values?
The model doesn't know anything about calorie intake, macronutrients, or exercise; it only knows about the past week of weight data.
If you have enough weight data, you can predict your progress without micromanaging variables and introducing more complexity.
Your behaviours are what influence your success
In addition to tracking weight data, you can track behaviours that influence your weight. The most popular way of doing this is to use an app to record your food intake and exercise.
Instead of zooming in on calories and grams of protein, you should look at your top-level behaviours:
- Did you plan and track your food today?
- Did you eat out a lot?
- Did you stay up late last night?
You can log those behaviours daily with your weight data and use machine learning to identify the most important ones.
Here I applied the XGBoost algorithm on some anonymised client data to classify their behaviours based on how they influence weight, ranking them by importance. Note that the ranking doesn't discriminate between weight gain or weight loss, it only cares about how strongly those behaviours predict change in weight.
You can see the most important features of the data selected by the algorithm were:
- Eating out.
- Tracking or not tracking macronutrients.
- Introducing a more aggressive calorie deficit.
Intuitively it makes sense: eating out introduces a lot of variability in calorie intake, tracking consistently helps maintain a calorie deficit, and reducing calories significantly promotes weight loss.
Your behaviours are what influence your success, not the specific details of how you set up your diet.
It's important to remember that your data may lead to completely different conclusions. You need a lot of data for this to work properly, don't expect meaningful results if you've only been tracking for a few weeks.
This approach works over longer timescales, like 3-12 months, to inform behaviour change and support sustainable weight loss or weight maintenance, not to optimise short term diets.
How to take action on this
Here are the three things you can focus on right now:
- Sample your weight measurement daily in the same state and at the same time.
- Use a moving average to assess progress not the raw data.
- Be consistent with strategic behaviours like tracking your food intake, preparing your meals, and prioritising restful sleep.