The problem most people run into is that they ingest too many calories, which are then stored as body fat as an evolutionary "backup plan". You see, our ancestors didn't always have a KFC sitting on the nearby corner, so they actually had times of famine. Our bodies store adipose (fat) tissue for when we are in need of energy when those hunting and gathering times aren't so good.
People have to ingest calories in order to survive. Foods tend to contain other things in them such as nutrients that make them ideal for our calorie consumption. Fruits, vegetables, whole grains, lean proteins, healthy fats are all nutrient dense. What this means, is that healthy foods give you the most "bang for your buck". You want to aim to get as many nutrients and vitamins in your body through natural sources as possible, while keeping your calorie count low, in order to maximize your metabolism and keep your weight down, while maintaining good health.
Liquid calories can therefore be a major pitfall for a lot of the population. Virtually all sources of beverages that people consume (other than water) have high calorie counts, with very little nutrient payoff. Take sodas for example, most of these beverages can contain anywhere from 8-10 teaspoons of sugar....per can! Visually picture yourself scooping 10 teaspoons of sugar into a can, then filling the rest with water. There doesn't leave much room for water, let alone any vitamins or nutrients.
Believe it or not, sodas can actually play a part in a person's diet, that is if they are a highly active person. Take, for example, a marathon runner. If they were to drink a can of soda before a race, that sugar would be digested and burned off in no time from their high activity level. Most people, however, sit down and enjoy a can with a high-calorie meal while watching tv. Those calories coming from the sugar in the soda are either used right away for high-energy activity (which they aren't) or are packed away for future use (aka, body fat).
Alright, fine, let's give up soda. Many people have taken this pledge (including myself) to give up soft drinks, so now what? I find milk to be a good alternative, but watch your nutritional labels. Milk is high-calorie because it contains fat and protein as well as natural and added sugars. You may be surprised at how much sugar is in your glass of milk. Look at the sugar count per cup (250mL), in grams, of milk, and you may be surprised how much is actually in there. Not only that, as you get closer to skim milk, or in other words, less fat, companies add in even more sugar in order to make sure the taste stands up. I personally like to enjoy either 1 or 2% milk in moderation as milk can provide a lot of vitamins and nutrients such as calcium!
Alright, so milk is a nice substitute for soda, but keep it in moderation. How about fruit juices then? Many companies are jumping on this bandwagon so to speak as they are finding the need to produce what the public is asking for. I will just come out and say it, fruit juices can be just as bad, if not worse than sodas. They can be very high in sugar with potentially little to no nutrients left. The act of processing fruit juices to get the product to your grocery shelf can remove many of the nutritional benefits of the product, not to mention the removal of fiber, which is helpful in slowing the digestion of eating fruit whole. Try and stick to real fruit juices that have no added sugars, and often times, you can "cut" the juice by filling half a glass of juice with the other half water and still enjoy the flavor, minus all of those extra calories.
Coffee is actually zero-calorie. There are numerous health benefits to drinking coffee that have been reported in the recent past. Let's face it, coffee is one of the most widely-consumed beverages in human history, so it is no surprise that it is also one of the most widely-researched (pros and cons). I could write an entire blog on coffee consumption, which I can in the future, but for now, you can make your own conclusions on this. Chances are, if you are currently a coffee consumer, I may not change your mind either way, and vice versa. Just keep this in mind, coffee can suddenly become very high-calorie by adding too much cream, sugar, or flavored coffees to the mix. If you can handle black coffee, that is the best, but I understand some people like to add some sugar and (I recommend) milk to help the taste, so 1 or 2 teaspoons of sugar in your coffee in the morning will not make or break your diet assuming you are ingesting a well-rounded diet throughout the day.
Alcohols, like soda, are nutritional bombs. Just to give you an idea of calorie breakdowns, and where our dietary energy comes from; fats are 9 calories/gram, proteins and carbohydrates are 4 calories/gram, and alcohol is 7 calories/gram. Fats, proteins, and carbohydrates are generally packaged with nutrients and dietary benefits when they are consumed, whereas alcohol is essentially useless in the body and is just used as energy. Yes, like coffee, there have been many studies done on alcohol trying to prove or disprove its need in the human diet. I will say that there appears to be some health benefits to having a drink now and then to help relax, and lower blood pressure, but many people do not stick to their daily recommended intake. Not only is alcohol itself high-calorie, but most people do not drink alcohol on its own, they mix it with sodas or drink it as beer or wine, which can all heighten those calorie counts.
I find it so discouraging to see some people that are trying so hard to exercise and eat somewhat respectively, but then literally pour away their potential health benefits and gains by consuming large quantities of calories through needless liquid sources. The human body has evolved to feel "full" from eating solid foods. We do not get that same response from drinking our calories, which I think plays a part in the consumption of large numbers of calories being consumed. If people were to make a switch to drinking just water, milk (in moderation), and tea (zero-cal green teas, etc.), they could literally cut hundreds of calories out of their diets every day which that switch alone can account to pounds lost over months and years!