Side effects of fasting include dizziness, headaches, low blood sugar, muscle aches, weakness, and fatigue. Prolonged fasting can lead to anemia, a weakened immune system, liver and kidney problems, and irregular heartbeat. Fasting can also result in vitamin and mineral deficiencies, muscle breakdown, and diarrhea. When you drink laxative concoctions during a fast, there is an increased risk of fluid imbalance and dehydration.
Physiologically, calorie restriction has been shown in animals to increase lifespan and improve tolerance to various metabolic stresses in the body.  Although the evidence for caloric restriction in animal studies is strong, there is less convincing evidence in human studies. Proponents of the diet believe that the stress of intermittent fasting causes an immune response that repairs cells and produces positive metabolic changes (reduction in triglycerides, LDL cholesterol, blood pressure, weight, fat mass, blood glucose). [3,5] An understandable concern of this diet is that followers will overeat on non-fasting days to compensate for calories lost during fasting. However, studies have not shown this to be true when compared with other weight loss methods. 
Not much of a coffee drinker? Tea is also a natural diuretic, and types of herbal tea such as dandelion or fennel root can also lend a hand. In fact: When a recent study compared the metabolic effect of green tea (in extract) with that of a placebo, researchers found that the green-tea drinkers burned about 70 additional calories in a 24-hour period.
“When clients come to me, many of them have been through the diet wringer. They’ve tried every fad and gimmick and, of course, they’ve failed to maintain long-term success. The key to weight loss is to never feel like you’re on a diet, because diets don’t work. If you feel deprived, you will never make it past a few weeks. The only way to achieve long-term weight loss is to learn to appreciate food as fuel and slowly replaced processed food that cannot properly energize the body with real food that can. After a while this will become second nature and won’t feel like a daily struggle.” — Laura Burak, MS, RD, CDN
It sounds silly, but switching which hand you eat with can save you calories, and help boost weight loss. “It takes 15 minutes for your brain to realize that you’re full,” celebrity personal trainer Jay Cardiello told us in our article over 40 weight loss tips. “To give your mind time to catch up to your mouth, simply switch your fork to non-dominate hand. It may be frustrating, but it’s a simple and unnoticeable way to curb overeating and lose weight.”
“Eat vegetables before or with meals. Whether you are hungry on your way home or right when you walk in the door, snacking on veggies can help you keep your portions in check once you sit down to a meal. I also recommend starting your dinner with a vegetable salad or vegetable soup to fill you up and prevent overeating. — Ilyse Schapiro, MS, RD, CDN, author of Should I Scoop Out My Bagel?
All meals are important, but breakfast is what helps you start your day on the right track. The best, heartiest breakfasts are ones that will fill you up, keep you satisfied, and stave off cravings later in the day. Aim to eat anywhere between 400 and 500 calories for your morning meal, and make sure you're including a source of lean protein plus filling fat (e.g., eggs, unsweetened Greek yogurt, nuts, or nut butters) and fiber (veggies, fruit, or 100% whole grains). Starting your day with a blood sugar-stabilizing blend of nutrients will help you slim down without sacrifice.
Slimmers normally avoid nuts like the plague as they’re so high in calories. But, eaten in the right way, they could be your best friend when it comes to battling the bulge, according to natural health expert Michael van Straten. He has devised this week-long diet which uses nuts and muesli to help you lose up to half a stone while still providing your body with everything it needs. Lose weight fast on the Nut and Muesli Diet
If you’ve been eating fast food for years, get real about your approach: You’re probably not going to stick to an organic, gluten-free, paleo overhaul for very long. "You want to change as little as possible to create calorie deficit," says Dr. Seltzer, who insists the best way to support sustainable weight loss is to incorporate small changes into existing habits. So instead of giving up your daily BLT bagels in favor of an egg-white wrap, try ordering your sandwich on a lighter English muffin. Or say you eat a snack bar every afternoon: Swap your 300-calorie bar for a 150-calorie alternative. "Your brain will feel the same way about it, so you won’t feel deprived," he says.