In today's 'things you already suspected but couldn't prove' news, science has shown that dieting and weight loss works differently for different people. If you've ever known anyone who can subsist on takeaways and wine and still look like a Victoria's Secret Angel, and felt like you gain weight just looking at a doughnut, this is your 'told ya so' moment.
In fact, there's been two studies that show dieting's not a fair fight. In the first study, Israeli researchers looked at how different people react to the same foods, and determined that some us react to some foods in a way that could lead to weight gain, while others don't. The study was published in the journal Cell, and used 800 healthy volunteers rigged up to blood sugar monitors. After tracking all their meals for a week (with them eating the same breakfast to add some consistency), the researchers were surprised to find that even seemingly-innocent foods like tomatoes made some people's blood sugar spike.
Your blood sugar is just one way that your body reacts to food - for example, a huge blood sugar spike will tell your body "I've got enough energy here!", and so you stop burning fat and start laying it down instead. You'd expect a spike from the aforementioned doughnut - but not from a tomato.
That's not the only thing that effects your ability to lose weight. Certain gut microbes can also produce higher blood-sugar responses, as well as genetics and exercises. These reactions are called 'Postprandial Gylcemic Responses' or PPGR, and they're why different people can or cannot lose weight following the same diet plan, because they're unique to each person. It's worth noting that aside from weight gain, high blood sugar can lead to diabetes and heart conditions.
The second study at the University of Cambridge isolated a protein, sLR11, that seems like it can inhibit your ability to burn fat. The fat-burning process in question is called thermogenesis, and is also what helps us burn fat to stay warm. The researchers found, by looking at blood samples from 156 people, that the amount of this protein we have increases with age, our BMI and amount of visceral and subcutaneous fat. They're suggesting that the protein makes our bodies too good at holding on to fat, as it hinders our metabolism. Basically, some people will be able to lose weight quickly, while others will cling onto it.
The upshot? While researchers are trying to calculate an algorithm that will accurately predict how your body reacts to certain foods, and therefore create the perfect diet for you, don't beat yourself up if you're trying to lose pounds and it's not working.