There were 3 different studies done on this topic and these studies told us information about the metabolism and how it works.
Study 1- A study done by Frankenfield,2005. In this study, he wanted to look if predictive equations actually matched people’s metabolism(BMR) in healthy non-obese adults and obese adults.
70% of subjects were predicted accurately (82% of non-obese). When people are obese it’s much more difficult to predict their BMR but 70% of the time it was accurate based on the predictive equations so these people didn’t have a slow metabolism, however, for the majority of the time if anything, they underestimated their BMR so they thought that they were burning fewer calories than they actually were which would be the flip reverse of what we would expect.
The maximum underestimate being 20% and the maximum overestimate being 15% of measured BMR. Lots of these people that were measured, the predictive equations were close to actually being correct. They didn’t have slow or fast metabolisms regardless of themselves being obese.
Study 2- Does basal metabolic rate predict weight gain?
This question was looked into in 2016 by Anthanont and Jensen. They asked the question: “does basal metabolic rate predict weight gain?”
They took the BMR and body composition of 757 participants who currently weight stable so they weren’t losing or gaining weight. This was done over a period of 7 years.
They followed up with the participants at least 3 years later to check how much weight they’d gained.
Participants were ranked in sizes of their BMR and they looked at the highest percentage at the top and the lowest BMR at the bottom. When adjusted for weight, some people did have fast metabolisms(higher BMRS) than you’d expect and some people had slow ones.
They took the top 15% with their BMR of an average of 2,000 calories per day (BMI 27.4).
They took the lowest BMR average of 1,500 calories per day (BMI 28.3). As we can see when we compare the top of the group to the bottom there is a difference in these people’s metabolism by up to 500 calories per day, so even at the same weight the people in the top 15% were burning 500 calories more than the people in the lowest 15% of these participants.
So what does this mean for weight gain?
The study concluded that rates of weight gain were not greater in the bottom BMR group compared to the top BMR group, they were burning 500 more calories a day and they still gained the same amount of weight as the people in the lower BMR group so realistically metabolism actually played very little role. They concluded that adults with low BMR’s(slow metabolisms) are not uniquely predisposed to future weight gain.
Adults with BMR’s that are well below predicted BMR’s do not gain more weight than do adults with BMR’s that are well above predicted BMR’s. Despite a 500 calorie a day difference between the 2 groups. Basically, there was no difference in their weight gain in the 2 groups even though 1 group had slow metabolisms and 1 group had fast metabolisms.
This data indicates that in a typical majorly caucasian person(the ethnicity of the groups had to be stated because there are slight variances), that variations in BMR are not responsible for tendencies toward weight gain so unless you have a medically significant or clinically recognised slow metabolism then your metabolism is not what’s holding you back from weight loss.
Further, from the statement Anthanont and Jensen said that in the real world, people start and stop diets, exercise programs and medications that may affect weight. They suggest that these factors are far more effective than BMR is in predisposing individuals to weight gain.
The implication of their findings is that adults with low BMR’s either find a way to eat less or expend for energy in physical activity than do those with high BMR’s under free-living conditions. This means that people tend to find how many calories that they can have to maintain their weight and they try to stay within that amount.
Even if you have got a fast metabolism some people tend to overeat anyway and they tend to gain weight so having a slow metabolism at this point isn’t really indictor of weight gain.
Study 3- Does basal metabolic rate predict weight gain?
In a very recent study that was done in 2017 by a person called Christensen, “The associations of resting metabolic rate with chronic conditions and weight loss”.
They took the data in this study from 359 participants that attend a weight loss clinic over the period of 6 years so from 2008-2014 and over 12 months of treatment during that time in the clinic, on average men lost 8kg and women lost 5.5kg.
Regardless of the gender, BMR(metabolism) was not associated with weight loss so, over the course of these 6 years, the 339 people that they looked at, on average people lost 8kg and this didn’t matter if they had a faster BMR or a higher BMR than expected it was not associated with weight loss.
Christensen said, “This study suggests that when patients have prescribed a similar caloric deficit, those with a low baseline BMR do not appear to be at a disadvantage for losing weight”.
Simply put, this means that people with a higher or a faster metabolism will be able to lose weight on higher calories but when we put people into a calorie deficit whether that be one person is cutting on 2,000 calories, another person is doing 1,500 calories they will lose the same amount of weight. There is no reason as to why they can’t lose weight.
What we should take from this is that the vast majority of us are not doomed to a lifetime of weight gain. We can do something about it. The ball is in our court.
What it comes down to- Even if we, for the vast majority of us, if we’re overweight we don’t have slow metabolisms but even if we do, we’ve shown that it doesn’t make a difference when it comes to losing weight. We can still lose weight.