Name: Ping Wu Age: 15 Breakfast: Cake, an egg or cornflakes; milk Lunch: Bowl of vegetables, bowl of noodles, kiwi fruit; grape juice Snack: Two bananas Dinner: Fried rice; orange or grape juice Eating out with family: McDonalds once a week, has three chicken wings or hamburger and French fries Loves: Cheese. 'Sometimes, I have a slice of cheese on its own, or melt it over rice.' Hates: Ginger and shallots Exercise: Stretching exercises every day. Badminton, tennis or running for about 40 minutes once a week Ping asks: 'Sometimes when I eat a lot of sweets, I feel as if my brain is blocked and I can't think properly. What's happening?' Wynnie says: Our brains function best on a small steady supply of sugar. At any given time, our blood carries only around a teaspoon of sugar, which is sufficient to meet the energy requirements for our regular activities. When we eat too many sweets, our body is suddenly bombarded with an excess of sugar. Our body responds to this by making insulin. This hormone tells our body cells to take the excess sugar out of the bloodstream. The result of eating a lot of sweets at one time is an immediate energy boost, followed by a sudden drop of energy as insulin clears the sugar away from the blood into our body cells. The increase of sugar in the bloodstream causes a sharp rise in adrenaline. This 'fight or flight' hormone unfortunately increases our stress levels and reduces our ability to think and function efficiently. Recent research at the University of Virginia in the US found that brain performance is impaired in the short term when a person has too much blood sugar. They tested a group of adults with diabetes over a period of four weeks. They found that verbal fluency and mental arithmetic ability slowed as blood sugar levels increased. The UK Food Standards Agency recommends that children and adults only eat sweets and sticky foods occasionally or in small amounts. Chocolates and sweets are usually high in sugar and low in vitamins and minerals, so should only make up a very small part of your diet. Wynnie Chan is a British-trained nutritionist. If you've got a question for her or would like to be featured in this column, e-mail email@example.com Tips for avoiding brain fog Eat a balanced breakfast: According to research published in 2003, children who only ate sugary snacks and fizzy drinks for breakfast performed at levels equivalent to a 70-year-old when their memory and attention span were tested. Protein and carbohydrates work best to boost brain power e.g. beans or eggs on toast Eat oily fish: Omega-3 fats, found in oily fish, boost the performance of your brain. Eat salmon, mackerel, fresh tuna or trout a couple of times a week Eat fruits and vegetables: These contain antioxidants which soak up harmful free radicals which promote premature ageing. Keep your brain in tip-top condition by snacking on fruits such as blueberries and strawberries.