Why can some people eat whatever they want but not gain weight?

We all have that one friend who can eat whatever they want and never gain weight, whereas for others, it's a minute on the lips and a lifetime on the hips. 

What's going on here? Is it that these people a have rapid off-the-charts metabolism? Is it that ours is super slow?

Now, it’s not wise to compare ourselves to others, but naturally, people do, so let’s explain what’s going on.

Prefer to watch than read? Then please check out the video below:

Why is it harder for me to lose weight?

Scientific research on metabolism

If we were to take you and your friend and overfed you by 1000 calories per day, what would happen? Well, if things were fair, they would gain the same amount as us, but life isn't fair, and even though you're both overconsuming by the same amount, that doesn't mean you'll both gain the same amount of weight. How one person's body utilises an extra 1000 calories can be vastly different to another. Check out this study done on the response to long-term overfeeding in identical twins where participants were overfed by 1000 calories per day six days a week for a total of 84 days during a 100-day period. The mean weight gain was 8.1 kg, but the range was 4.3 to 13.3 kg. So if you and your friend were to sit at either end of these two extremes, your friend would gain 4.3kg, and you'd gain over three times that - this largely comes down to genetic differences in metabolism! But what if you and your friend had the same metabolism? Is it still possible that your friend would find weight management much easier? Yes, there's more to this than just metabolism, other genetic factors play a role, and a big one is hunger!

Insatiable appetite

Some people experience much more hunger than others, and even though there are strategies we can implement to attenuate hunger, if the genetic hand we're dealt involves more hunger, it's obviously going to make controlling intake much harder. Alright Andy, well how about this one; let's say genetically, our metabolisms are matched, and we both experience a manageable amount of hunger, to the point where we can hit the same calories religiously. Surely in this example, we'd both lose the same weight? Not necessarily, as we need to consider energy expenditure, of course.

Overall activity levels

Some people are much more active than others, and even if you both follow the same training plan and match calories burned via training, this doesn't account for the calories you burn from NEAT. As mentioned in a video I did a few weeks ago; this is Non-Exercise Activity Thermogenesis. Check it out if you've not done so already, but essentially, it’s the calories we burn from subconscious movement, such as fidgeting, maintaining posture, and just generally moving around. One study where, again, they overfed participants by 1000 calories per day saw NEAT levels range from -98.3 to +692 calories per day.

So, you might eat an extra 1000 calories, hit a food coma and stop moving, whereas your friend burns most of that 1000 calories via subconscious movement. And that's not everything!

Multiple other factors can make weight management much more challenging for some than others, such as;

• Menopause

• Pregnancy

• Certain medical conditions

• Certain medications

• And Injuries

Knowing this, I think we can sympathise with people who are struggling with their weight from no fault of their own. And if you're struggling, hopefully, this will help you to better understand why that might be and allow you to be less hard on yourself.

The good news

The good news is that even if you have many of these factors against you, that doesn't mean you can't lose weight, just that it's harder, and in extreme examples, much harder. You'll lose weight the same way as your genetically gifted friend does, and that's by being in a caloric deficit. It's just that your calories might need to be much lower, and you have to be much more conscious of your activity levels. You need to work with the genetic hand you're dealt, except that it's going to be challenging and appreciate that you're not alone. There is someone out there with everything against them, but they are making great progress. Everyone can make positive changes to their body and health – just some of us have to work harder. And it's worth mentioning that if you feel you might have an underlying medical condition preventing you from making progress, such as hypothyroidism, then please reach out to your GP for help.