1. You had a marathon TV pig-fest. Never starve yourself the next day. This slows down metabolism, the opposite of what we want for you. Try a high-fiber, low glycemic breakfast. This will keep you feeling full longer and help keep you from splurging at lunch. Cut 500 total calories off the daily total (the average person needs about 2,000-2400 calories a day, will vary). This will help increase your energy.
2. You went boozing with friends. Drink lots of water. Alcohol dehydrates the body (impairing energy capacity and endurance). Drink 60-120 ounces of water (filtered) everyday. Eat fruits high in water content to help get the water in. This will help restore fluid balance and improve fat-burning. For the day, go for grilled poultry, plain nuts, and raw vegetables every 2-3 hours (no more than 4) to help combat swings in blood sugar and speed recovery.
3. You had a more than lazy business trip. Try high intensity workouts to get you back on track. The intensity of the workout is more important than the duration (30 minutes is ideal including warm up). Shorten the time between sets, increase your reps, or add sets to your workout to help maintain high intensity. Eat clean and be "hyper-ware" of your diet. Base your meals around fruits, vegetables, and select whole-grains. Stick to lean, healthy proteins and limit added sugars and high-fat snacks.