You're training like a machine and you're dieting hard, but you just can't shed the body fat. Sound familiar?

It's the same story for so many of us - and not being able to achieve the physique you want is frustrating and can make you want to give the whole fitness thing up. Firstly it could very well be a question of how many calories you're eating. But equally it could be what you're eating that's the problem. While allergies are thankfully rare, food intolerances are pretty common and many people don't realise that their food could be causing problems including fatigue, bloating, migraines and digestive problems. Personal trainer Matt Perry from Kent, in southern England, was one of these people. The 42-year-old is a regular triathlon competitor, but was struggling with weight loss and low energy levels. But Matt underwent a series of tests with food intolerance experts and found 11 'trigger foods' that were causing problems and holding back his fitness. After eliminating the 11 offending foods from his diet, including wheat, yeast, soya and milk, he lost 17lbs in just a month and his waist dropped from 36in to 32in. Other foods he cut from his eating plan were egg white and yolk, crustaceans, lentils, peanuts, mustard seed and grape, which he replaced with substitute ingredients. Matt said:

“When I first got my test results I was shocked to find that I was sensitive to several of my staple food groups. I wasn’t expecting there to be so many. “I used to eat anything I fancied - a pasty, an on-the-go sandwich, pizza, cheese - it was daunting to face cutting out a lot of my favourite ingredients, but also a relief to realise that this was the cause of my problems.”

Food intolerances come in many different forms. Common problems include enzyme deficiencies like lactose, coeliac disease where reactions to gluten proteins damage the gut wall, and chemical sensitivities like E numbers and caffeine. Food intolerances can cause chronic inflammation in the body and, according to FoodIntol, the main culprits are sensitivities to dairy, gluten, yeast and corn found commonly in the modern diet. Inflammation can cause all sorts of health problems if not dealt with. It can certainly make weight loss harder, slow down your metabolism and influence hunger levels so you eat more. It can also make you more resistant to insulin and so you store more fat. Matt, who was struggling with low energy and had trouble sleeping, implemented the dietary changes after taking YorkTest's analysis of his IgG reaction to 158 food and drinks. He said:

“I lost 17lbs and over an inch from my waist less than five weeks after implementing my new diet, but it’s not just about the weight-loss, my whole outlook has changed. “One of the most noticeable improvements is my higher energy levels; I am more focused and clear-headed. Personally, it’s now more important that I feel good and perform well.”

As well as positive body composition changes, Matt claims it has enhanced his athletic performance during the triathlon season.

“In the first triathlon I competed in after integrating the changes, I knocked 17 minutes off my personal best time," he said. "There is no doubt that this was down to a combination of my new eating regime and positive new mind-set. It just goes to show that a simple test and re-education of your eating habits can turn your life around.”

Now his diet consists of an omelette, protein shake with oat milk, chicken salad or spicy chicken salad wrap and spaghetti bolognese with free-from pasta. Matt added: “I consciously think about what I eat now and cook a lot from scratch. I also buy free-from foods so I’m not missing out on biscuits and snacks. As long as I feel comfortable and my clothes fit, I’m happy." Dr Gill Hart, Scientific Director at YorkTest, explained:

“Knowing what to eat and drink, and importantly, what to avoid and why, can be mystifying, especially for those experiencing negative symptoms such as low energy levels. “We take a personal approach to our clients and their symptoms by championing the ‘food fingerprint’ and encouraging anyone having adverse reactions to food and drink to investigate food personalisation.”