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The Science Behind Dieting & Weight Loss

The Science Behind Dieting & Weight Loss

It’s about that time again. The men are stepping up their game in the weight room and the ladies are visiting the tanning beds. Why? Because summer is just around the corner. Are you going to be ready?

Here’s an overview of a science based approach of what your diet needs to consist of in order to help you get to your leanest self yet. Let’s go!

Calories are King

Everyone is always looking for the newest way to lose weight and people tend to go for the latest and greatest fad diet out on the market. The big picture that many of us don’t get is that the total amount of calories that you are consuming will be the single most important factor in getting you the results that you want. The types of foods you eat are influential of your results, but only to a point.

science of weight loss

If you’re eating 4,000 calories of broccoli, chicken breast, and brown rice, but maintain weight on 2,700 calories, you will definitely not give your body the proper environment to lose fat. While those foods are not necessarily bad foods, the amount of which you are eating will in no way allow your body to lose fat. You need to make sure that the amount of calories you’re consuming is below your maintenance calorie amount.

When you’re constructing a diet, make sure the amount of calories you’re setting yourself to aim for every day is below you’re maintenance intake.


As discussed previously, the amount of calories that you set for yourself to consume daily will be the main focus of any goal, but the macronutrient profile of how you’re getting your calories comes in a close second.

When on a calorie restrictive diet, protein and fiber are going to reign as the supreme macronutrients. And there are several reasons as to why getting enough protein and fiber is such a priority. When you’re dieting to lose fat, you want your body to maintain as much muscle mass as possible. Having a surplus of protein in your diet will allow your muscles to have ample amounts of amino acids in your system to help you keep that muscle that you worked so hard for. To help absorb all of that protein, a good amount of fiber will be needed. Another reason why protein and fiber are so important, is that they are both ergogenic aids!

When you consume food, the process of how you digest and distribute nutrients is different and varies from what kind of foods are in your diet. The thermic effect of food (TEF) is a measure of the increase in your metabolic rate after consuming food. The TEF values are percentages of the calories you consume for that specific macronutrient. For fats and carbohydrates, about 5% of the calories you consume of fats and carbs are used in the digestion process. For protein and fiber, about 25% of the calories you consume are used to assimilate the content you just brought in to your system. That is a massive difference when comparing to fats and carbohydrates.

science of weight loss

So, if you’re taking in more protein and fiber throughout the day, the more energy turnover will be encouraged and the amount of calories you’ll be burning at rest will be much greater. Protein and fiber are also high on the satiety scale. Hunger can become a major issue in a calorie restrictive state. Having a good amount of protein and fiber from meal to meal will help you feel fuller longer and help keep you from getting cravings. An amount of at least 40 grams of fiber a day and at least 1.2g of protein per pound of bodyweight. It sounds like a lot of protein, but it’s something you don’t want to count out. In a study done by McMaster University, obese individuals were given different amounts of protein while being on a calorie deficit diet and participating in resistance training .1 Individuals were given either .5 g of protein per pound of bodyweight or 1.0g per pound of bodyweight. The group that was receiving more protein not only gained more muscle, but was able to burn more fat! So keeping your protein high will be imperative for optimal results.

Fats and carbohydrates are the two macronutrients left after protein and fiber. Fats are essential for aiding in proper hormone regulation during a dieting phase. Fats should be anywhere between 15% and 25% of your total calories. Carbohydrates are your body’s main fuel source. Most will recommend cutting out carbohydrates, but if you’re in the gym regularly, you’re going to need that extra fuel. As long as your calories are below maintenance, the amount of carbohydrates that you’re taking in should not be too relevant. Filling in what calories are left after determining protein and fat intake, with carbohydrates, is your best bet.

Calorie Cycling

Dieting is usually something that everyone absolutely dreads. What if I was to tell you that extended periods of dieting could actually be working against you? Long periods of dieting are what have been previously thought to be the most effective way to lose fat, but science shows that there are several maladaptations that incur when in a calorie restrictive state for long time periods.

The number one of these maladaptations is the change in your metabolism. When someone is dieting down for weeks on end on low calories, your body is constantly adapting to try and survive on the lower amount of calories that you are now taking in. Your metabolism shifts as a result. Your body doesn’t care about looking good, your body cares about survival. One of the few studies on this topic to date investigated cycles of 11 days dieting and 3 days at maintenance versus continuous dieting at low calories.2 Despite the fact that the total calories were the same for each group, the group that cycled their calories after 11 days of dieting lost more weight! Not only that, these individuals kept the weight off during the maintenance phase. This could have been due to the fact that they were able to keep their metabolism from making drastic adaptations. Having your metabolism in a good state after a diet could mean wonders for not gaining all that weight back.

science of weight loss

The other main changes in your body is your body’s changes of the hormones leptin and ghrelin. These are the two main hormones that affect your appetite. We all know that our appetite can be a major factor on how we eat. Leptin is our appetite suppressing hormone and ghrelin is our appetite inducing hormone. In a calorie restrictive state, leptin decreases and ghrelin increases. This is a double whammy to our hunger! To offset some of these hormonal changes, calorie shifting for a temporary time period during the diet could be the answer.3 Periodic refeed days have been the norm for several, but it seems that hormones need a longer period of time to return back to baseline than just a single day.

 A decent approach to calorie shifting could be 3-4 weeks in a calorie restrictive state with 1-2 weeks of maintenance following or having a few continuous days of maintenance within a 2 week dieting period similar to what the study has shown. Not only will these maintenance periods be biologically beneficial, it’ll be easier on your mind as you’ll have a little bit more freedom.

Take-Home Message

To wrap up, when dieting, one should remember these key points:

  • Calories are your greatest factor
  • Keep protein and fiber high
  • Shift your calories occasionally to avoid maladaptations

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

  1. Thomas M Longland, Sara Y Oikawa, Cameron J Mitchell, Michaela C Devries, & Stuart M Phillips.(2016). Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. American Journal of Clinical Nutrition, ajcn119339.
  2. Davoodi, S. H., Ajami, M., Ayatollahi, S. A., Dowlatshahi, K., Javedan, G., & Pazoki-Toroudi, H. R. (2014). Calorie Shifting Diet Versus Calorie Restriction Diet: A Comparative Clinical Trial Study. International Journal of Preventive Medicine, 5(4), 447.
  1. Dirlewanger, M., Di Vetta, V., Guenat, E., Battilana, P., Seematter, G., Schneiter, P., … & Tappy, L. (2000). Effects of short-term carbohydrate or fat overfeeding on energy expenditure and plasma leptin concentrations in healthy female subjects. International Journal of Obesity, 24(11), 1413-1418.



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