Start-up life often means stressed out, 24-hour workdays. When coffee doesn't cut it, some entrepreneurs turn to energy drinks like Red Bull and Monster Energy. But these beverages not only make your energy spike and crash, but they can also take a toll on your body. Just ask my client Lynn, who owns a Web design firm. Lynn had always eaten healthy and worked out religiously, but as her company grew, she started skipping meals and relying on energy drinks to help her meet the demands of her busy day. Soon, Lynn began experiencing bouts of dizziness and fatigue. She reluctantly dragged herself to a doctor and was diagnosed with a heart arrhythmia. She was gaining weight too.

After Lynn and I reviewed everything that she was eating and drinking, she revealed she had been drinking about two energy drinks a day. The average can contains a whopping 30 grams of sugar and 180 mg of caffeine. That combo can make you feel anxious and stressed in the short term and then exhausted after the effects wear off and your blood sugar plummets. Not only that, but ingesting an extra four tablespoons of sugar ever day--the amount in just two cans--will absolutely add weight to your midsection.

There are plenty of healthy alternatives that can help you feel energized--without the negative effects of loads of caffeine and sugar. Made from natural ingredients, here are five healthy options that will help you stay focused throughout the day.

1. Protein smoothies. Blending fruit and protein powder will boost your energy in a natural and sustainable way. If you are being mindful of your weight, use berries, which are low in sugar, as your main fruit. Don't forget to add the protein powder, which will provide lasting energy and better help maintain focus and concentration. If you don't have time to make your own, head over to Jamba Juice.

 2. Green drinks. These juices are a combination of vegetables (and a little fruit to make them palatable). One 16-ounce drink may provide the equivalent of four to six servings of vegetables and one or two servings of fruits. Loaded with vitamins, minerals, and enzymes, green drinks help nourish and hydrate you, which will keep you feeling focused all afternoon. You can find them at many places, including Juice Generation, BluePrint, and Organic Avenue.

3. Solixir energy drinks. Created by health fanatic and entrepreneur Scott Lerner, Solixir makes energy drinks with natural ingredients and very little sugar. Two of the company's beverages are particularly helpful for stamina and concentration--without the spikes and crashes of many energy drinks. Using natural ingredients, such as ginseng, and a small amount of caffeine, the Awake formula is great for a subtle afternoon pick-me-up. Or, for a caffeine-free concentration boost, try Think, which contains gingko biloba.

4. Water. Amazingly enough, simple tap water can have profound effects on your energy levels. Dehydration makes you feel tired, hungry, and unable to concentrate. Being dehydrated can also have a negative impact on your digestion and blood pressure. Instead of shooting for the standard eight glasses, just have a glass of water every time you feel tired or hungry.

5. Coconut water. If drinking plain water bores you, try this. It has about the same electrolyte balance as your blood does, providing the minerals you need to nourish your circulatory system in a healthy way. It is also a great source of potassium, which has been found to help keep blood pressure in check. Hydrating your body can help you feel more energized, so coconut water can be a refreshing pick-me-up in the middle of a hectic day.