How to Gain Unwanted Weight

Two schools of thought exist on why we gain unwanted weight: a) excessive calorie intake and lack of physical activity, and b) poor quality of nutrient intake (e.g. ratio of carbohydrates, fats, protein). Whether you are in the quantity or quality camp, very slight changes, compounded over time, make a very significant long-term impact. Scientist call this "sensitive dependence on initial conditions," also known as the butterfly effect.

Gaining 20 pounds over 20 years (e.g. between graduating high school and a 20-year reunion) is common and likely results from numerous factors -- not simply more calories in than out. For argument's sake, though, let us consider the calories-in/calories-out approach -- 20 pounds over 20 years is a positive difference of just 10 calories per day. Ten calories equates to less than a teaspoon of sugar or a one-minute jog.

This positive energy balance of 10 calories per day is comparable to the average increase in Americans' weight over the past 20 years. According to National Health and Nutrition Examination Survey data, over two-thirds (nearly 70 percent) of adults are currently overweight or obese. Data extrapolated from this survey equate to an average gain of 0.5 to 1 pounds per year, which is roughly five to 10 extra calories (either more intake or less output).

Therefore, gaining weight over time is incredibly easy. If you have a goal to gain unwanted weight over the next few years, simply follow these guidelines:

1. Drink your calories.

The fastest way to gain unwanted weight is to drink your calories -- soda, milk, juice, sweetened tea/coffee and alcohol intake can easily total 300-plus calories daily. And if we count calories, 300 extra calories per day equates to nearly one pound per week of weight gain.

If we do not count calories, such drinks typically have low nutrient density (i.e. no bang for their buck). Many Americans continue to replace nutrient-dense drinks like milk with soda (which, in this author's opinion, is the worst food/beverage in the world), decreasing the overall quality of diet, without necessarily affecting calorie intake. Poor nutrient intake may influence our hormone system and alter how we store fat -- thus, both excess intake and low-quality intake can lead to fat gain.

[Read: How to Lose 50 Pounds Without Really Trying

.]

2. Eat beige food.

A shift towards nutrient-dense foods will not only help manage weight, but improve overall health, including how you recover from exercise, sleep at night and ward-off disease. Think about your last few meals -- what color(s) were on your plate or in your bowl? Variations of meat, bread and potatoes usually end up very beige -- and a beige diet is suboptimal.

Aim for at least three colors on your plate with each meal and snack, and at least half of that plate filled with fruits and vegetables (primarily the latter). Sorry, a bag of Skittles does not count as three-plus colors; nor do various shades of any single color. You can also consider swapping your grains and starches for fruit -- that way, you can cut down on calorie-dense foods without starving yourself of healthy carbohydrates.

[See: U.S. News Best Diets .]

3. Follow every trend.

If they can name it and you have tried it -- Ornish, Atkins, South Beach, Paleo -- consider bucking the trend and focusing on the common denominators of fad diets. Any diet plan that "works" includes eating fewer calories, natural foods, nutrient-dense foods, high amounts of vegetables and low amounts of added-sugar.

Following a plan (which likely eliminates certain foods) for a lifetime wreaks havoc on your mindset and usually results in reversal to old habits or binges. Instead, gradually incorporate the above common denominators, and keep them part of your lifestyle permanently.

[Watch: How I Lost 100 Pounds .]

4. Blame your genes for your tight jeans.

The overweight and obesity epidemic is a product of our environment, not our genetics. Indeed, some people will end up overweight or obese due to genetics or medical conditions, but nowhere near 70 percent. The majority of the U.S. population does not have the "fat gene" or significant medical conditions causing obesity; standard distribution of the bell curve would indicate an approximately 5 percent obesity rate, regardless of diet and exercise choices. Data from the CDC show that every state currently has an obesity rate of at least 20 percent. Genetics do account for a portion of these rates, but by no means could they account for the dramatic change in obesity rates over the past 20 years (the obesity rates slideshow proves this theory, as the human genome has not changed at all since the 1980s).

5. Keep doing exactly what you are doing.

If your goal is to lose weight and it has yet to happen, maybe you should explore further outside of your comfort zone. To truly burn calories, you must exercise at an intensity level of mild discomfort or greater (or as permitted from a physician). And yes, ordering a salmon-topped salad with lemon wedges for your "dressing" at a sports bar may not excite you, but as mentioned -- small changes add up over time.

Basketball star Dwayne Wade recently stated that eating more vegetables to assist with his off-season weight loss was one of the hardest things he has ever done. Filling half your plate at each meal with vegetables and including at least three colors is challenging -- and it is supposed to be hard. But the results can also be extremely rewarding.

[Read: How to Know if You're Exercising Too Much .]

6. Focus only on nutrition and exercise.

Providing detailed behavior change advice is beyond my scope of practice; however, making significant, positive health changes is contingent on altering three primary tiers: food, activity and behavior. Before you change your habits, establish why you eat what you eat; how you can increase physical activity; what your barriers to better health are; and what practices were essential in your past success.

Self-assessment, goal planning, reflection and reevaluation are essential components to behavior change, which will allow the "nuts and bolts" of nutrition and exercise to fall into place.

Consider this scenario: a town of 1,000 people who grow their own food, cook every meal, drink water with meals, exercise an hour a day, five days per week (with at least 90 minutes per week of vigorous exercise), do not smoke, do not drink alcohol, laugh every day, and cope with stress. How many of them would be overweight or obese? In this author's opinion, far, far less than 650 (the equivalent of the average in most American cities).

The chances of this town existing are nil; however, how many of these habits do you currently exercise, and how many more could you incorporate into your daily routine? Truthfully, losing weight (or preventing the 20-pound gain over 20 years) is challenging. Weight maintenance and weight loss take self-control, will power, self-assessment, goal planning and almost constant re-evaluation and modification.

[Read: Diet Success Stories: Dieters Reveal How They Hit Their Target Body Weight .]

Justin Robinson is a Registered Sports Dietitian and Strength and Conditioning Coach who specializes in practical sports nutrition recommendations and functional conditioning techniques. Over the past 15 years, Justin has trained athletes from youth to professional level, including runners and triathletes, Major League Baseball players and U.S. Military Special Operations soldiers. Justin likes to practice what he preach and, thus, regularly completes in running, cycling and triathlon events. Follow him on Twitter at @JrobRD.