A few important notes before we begin:

We often use the term weight loss and fat loss interchangeably, it is important to recognise there is a difference between weight loss and fat loss, and it’s fat loss specifically we are aiming for.

It’s also important to note that although today’s topic can be a common reason many people struggle to lose weight, weight loss is much more complex than just one thing. Something to bear in mind when reading through today’s blog, we aren’t accusing in any way, and we also have to bear in mind that under-eating is something we have to be very mindful of. With that being said, we often find inaccuracies of food intake are quite common, when people are attempting to lose weight.

Under reporting

The science is clear, the accuracy of food reporting is pretty low. Across the board people do not track their food very accurately at all, tending to under report the number of calories they consume. This isn’t necessarily on purpose by any means, people have the best intentions when tracking their food. It is easy to fail to report all of the food they consume, even directly incorrectly input foods, or underestimate portion sizes.

In fact, even dieticians, whose job it is to give nutrition advice, even under-report their food intake. One study that included 10 dieticians (alongside 10 subjects of a similar age who weren’t dieticians) that were trained to provide a 7-day food diary and asked to report as accurately as possible, showed that the dieticians under reported their food intake on average by 223 calories a day [1]. The non-dietician’s group under reported by slightly more, averaging 429 calories a day under reported.

In fact one dietician was close to under reporting by 800 calories per day!

There was another study performed in 1992 on self-proclaimed ‘diet resistant’ individuals, who claimed to have failed to lose weight in the past even though they claimed they were eating around 1200 calories [2]. 

Astonishingly the average reported intake in the study by the subjects was ~1028 calories. But their actual intake was actually ~2081 calories. This is nearly 1000 calories that weren’t reported or accounted for and accounted for 47% of their calorie intake.

Also, interestingly in one study that showed participants ate back more calories after exercise [3], and in one of the groups they found that those who perceived the exercise session as stressful and unenjoyable consumed more calories than those who perceived the exercise session as being enjoyable.

When we combine how common under-reporting calorie intake is with how common over-reporting energy expenditure is. Compounded by with how common it is that people eat back more calories after exercise sessions than they have burned during exercise. We have a perfect storm for weight maintenance. 

[1] PMID: 12396160

[2] PMID: 1454084

[3] https://doi.org/10.1016/j.appet.2014.05.030