How long until over eating is noticeable on the scales?

This post ended up too long for Facebook so I thought I would post it here..

Something I would like your input explaining or at least your help exploring..

How long does it take to put on weight in a calorie surplus?
How long until over eating is noticeable on the scales?

There is no straight forward answer to this and it is obviously going to depend somewhat on the size of the surplus and also the individual. Nonetheless, there seems to be an interesting lag between increased calorie intake and increased weight gain.

Given this is an observation there is no right or wrong answer I am just interested in your thoughts..

And here are mine..

In the very short term lack of weight gain is unsurprising. You’re not going to pile on fat after 1 meal and you’re not going to drop body fat after 1 exercise session. This is a matter of the total magnitude of the calorie imbalance. Your body averages out calories in and calories out over time and your weight is a product of this. Small fluctuations are flattened out by this averaging.

When we consume food it goes through a digestive process. Food takes ~6-8hours to make its way through the stomach and small intestine and then continues to the large intestine where further digestion occurs and water is absorbed leaving the rest to be excreted. The energy taken from this food during digestion is then used by the body either as to fuel living- processes that keep you alive like breathing, movement and exercise. What is left is then stored as body fat.

Note: if no energy is left over after this then no body fat will be stores and you will not gain body fat. On the other hand if there is not enough energy from food coming in then your body will use stored body fat for its energy needs and you will lose fat.

Now that this is out the way I want to get on to the observation that even in the medium term (1-2 weeks) there seems to be a lag in weight gain while in a calorie surplus.

I don’t have an answer for this but I have come up with a few potential reasons:

1) Adaptation in order to defend a set weight.

Your body adapts in order to try and maintain a set weight examples of this include changes in activity level to offset a change in energy intake.

2) Increased heat production.

Meat sweats anyone? I often notice when I eat more I produce more heat.. the extent to which this contributes to total energy expenditure is likely very small but it could contribute over the course of the day.

3) You’re not actually eating as much as you think.

Maybe you aren’t in as big of a surplus as you might imagine. This may be especially true with ‘clean eater’. You could probably double most of your portions and still not be in a huge surplus if you are eating a diet based around lean meat and veg. Especially if you are coming from a deficit.
Example: You’ve been dieting for an event and then increase your calories but stick to the same types of food. You would have to eat A LOT more than when you were dieting to get you back to maintenance and then into a surplus.

It takes a lot of calories to put on noticeable weight. To put on 1 kg you would have to eat in excess of 7,000 extra calories. That is 1,000 extra calories a day for a week.  So, if you usually consume 2,000 calories a day to maintain your weight you would have to eat 3,000 a day for a week to put on 1kg of fat.
*Let’s ignore the fact that this is not an exact science as we are not robots for now*

4) Maybe the weight change takes longer than we think when we change our calories.

We know that the body tries to defend its set point. It would make sense that it might take a few days to maybe up to 2 weeks to see a shift in scale weight. Which leads to my next point, weight change isn’t a very precise measure. We fluctuate with water, menstrual cycle, training load, food volume, time of day..the list goes on, all of which can mask your fat gain or loss.

5) The scales aren’t a very sensitive measure.

It is also true that weight can’t measure changes in energy storage/fat until you have created a fairly big surplus or deficit. Let’s assume you need to actually gain 1kg (ignoring fluctuations) to measure a change in body fat. That means you need to consume 7,000 extra calories before you see the scale go up by 1kg. And as most of us fluctuate by 1-4kg daily anyway this is hard to spot initially.

I have rambled on enough.. I am interested to know if you or your clients have experienced this and how you think this might be explained?