Novak Djokovic's credits his success to a diet of mostly warm foods I want licorice tea!. Novak Djokovic reacts when offered a cold drink on court. Naturopath, nutritionist and herbalist Cassie Mendoza-Jones. EATING salads might seem super healthy but it can also be detrimental to digestion. A diet secret in Novak Djokovic's new book Serve to Win has let fans in on what Chinese medicine practitioners have known for centuries - that warms foods are better for us. In Djokovic's book, released last month, the men's No. 1 tennis player says he drinks warm water all day long because cold water slows digestion and "diverts blood away from where I want it - in my muscles." "The first thing I do out of bed is to drink a tall glass of room-temperature water," Djokovic says. The 26-year-old, who has climbed to the top of a brutally competitive sport during one of its most competitive eras, also reveals that he unwinds over a cup of warm licorice tea. His premise is rooted in Chinese medicine, which espouses the notion that digestion requires heat to be most effective. Therefore practitioners advocate a mostly warm, cooked diet. "Warming foods" like a stew are easy to digest. They believe that when we eat cooked food, some of the heat required for digestion is already supplied. As less energy is needed to create digestive heat, there's more energy available to aid digestion and absorption of nutrients. They believe cold and raw food and drink should be heated and people with weak digestion should avoid them altogether. In support of Djokovic's diet, which he credits to Igor Cetojevic - a "skinny, grey-haired, moustachioed" Serbian nutritionist living in Cyprus - Chinese medicine also advocates eliminating dairy and excess sugar. Warming foods - which should be chewed well and eaten while relaxed - include squash, carrots, potatoes, leeks, onions, rice, oats, butter, small amounts of animal protein, cooked fruits, cinnamon, nutmeg, black pepper and honey. Naturopath, nutritionist and herbalist Cassie Mendoza-Jones says heat relates to both the energy and temperature of foods. It refers to both. Plants that take longer to grow like carrot, parsnip and cabbage are energetically warming and you'd also want to slow cook them," she said. There could be no better warm food than soup, surely? There are things like cayenne pepper which tastes hot but we don't usually eat it as hot food. All of the vegetables that grow quickly like lettuce, radish and cucumber are really cooling. Room temp food is always better because your body doesn't have to use any energy to heat it up. Your body has to bring food up to a happy temperature before it's absorbed and passed through. For some people it's a bit of a shock to the system to have ice-cold water and you can feel your whole body cools down when you drink it. Hot or warm tea is definitely easier for your body to manage as it's more quickly absorbed. Ms Mendoza-Jones, who founded Elevate Vitality, says warming foods are particularly beneficial when unwell. "I have some clients who have such bad digestion that I need them to eat a lot of hot, warming foods until they feel better," she says. If you're feeling a little bit sick or down, or if you were feeding a baby or an elderly person, you would never give them raw carrot. You would give them slow cooked carrots or mashed carrot because it's easier to digest for most people and especially if you're body's a little bit stressed out. This salmon is served with walnuts, both warming foods which should be "chewed well and eaten while relaxed." If clients are really stressed, anxious or depressed I'm not going to instruct them to eat six carrots for all of the enzymes. I'm going to advise them to have chicken soup and broth and stews and slow-cooked foods that are easy to digest because when you're stressed your blood moves away from your organs and goes towards your brain and extremities (as it enters "fight-or-flight mode")." Bad circulation and an aversion to cold climates is also an indication that your body wants more warm foods. People who always feel cold should opt for warming foods while those who are always hot and sweat a lot are better off consuming more cooling foods like watermelon, apples, celery and peppermint. According to Chinese medicine, raw food diets are unsustainable and detrimental to health but the 27-year-old believes in balance. Quinoa is a great "warming food" but don't be fooled by the pumpkin. "I definitely ask people to have slow cooked warming foods in winter but you get a lot of beautiful enzymes from raw food but I think we need to have a combination of both," Ms Mendoza-Jones said. Sometimes people who are really irritable and angry or a bit uneasy and have insomnia can have too much heat in their body. If you then have something like chilli, which is really stimulating, or other really hot foods you can actually make your emotional-self much worse. The practitioner, based in Bondi, Sydney, said it's easy to incorporate more warming foods into the diet with a little research. "It has a lot more to do with the energetics, so foods that you wouldn't necessarily think are cooling might be - for example things like eggplant help to clear heat - which means you need to know more about each individual food," she said. Hot herbal tea is good for digestion. But avoid that cold glass of water. When fruits are juiced, their cooling nature and cleansing properties are concentrated. Most tropical summer fruits are cooling. Heating juices or cooking fruit makes them less cooling. If a warming food is eaten cold it won't be as warming. If you're having a cold food like dairy, perhaps mix it with room temperature muesli or something so it's not cold. You have to do your research or simply observe how you feel when you eat certain foods. I think once you understand it you can kind of apply it anywhere in your diet. Oats Quinoa Sweet rice Spelt Black beans Coconut Pine nuts Sunflower seeds Walnuts Asparagus Cabbage Kale Onion family (chives, garlic, leek, onion, scallions) Parsley Squash Parsnip Pear Strawberries Lemons and limes Peaches Oranges Grapes Apples Avocado Banana Grapefruit Wild rice Wheat Broccoli Celery Lettuce Spinach Pumpkin Radish Pineapple Raspberries Papaya Figs Apricots Buckwheat Corn Rye Rice Flaxseed Black sesame seeds