Weight Loss, or Fat Loss?

Let’s get down to it. Here we are going to cover the most basics (and essentials) of fat loss in order to give you the necessary understanding to complete this goal.

So, how do you successfully achieve fat loss? At the end of the day, it all comes down to diet and exercise. Energy balance is the net difference in calories consumed and burned. When just talking about plain ole ‘weight loss’, almost nothing else matters. Consuming calories from beverages vs. solid meals, burning calories by running vs. swimming, etc.… all the same. The bottom line really is that simple; if you eat more calories than your body uses (consistently), then you will gain weight.

Critical confusions – fat vs. weight loss

Starting at square one, let’s delineate the misleading term of ‘weight loss’.  Weight loss is specific to neither fat nor muscle. Depending on how one goes about loosing weight, two people may appear very different from each other after losing 10 pounds: lose just 10 lbs. of muscle and your body fat percentage will actually have increased, while 10 lbs. of fat loss would mean a drop in several percent body fat and an overall more healthy, aesthetic looking body image. What’s more, body weight can in fact fluctuate several pounds each day simply due to differences in your state of hydration (after all, we are 90% water).  So, when you step on the scale, realize that this is non-specific and very often misleading from the start. When setting a goal of  ‘weight loss’, one should actually focus on true ‘fat loss’ – something that can be favored depending on your diet, lifestyle and physical activity.

1)  Why the Calorie is King

The number one determinant when it comes to losing weight (fat or otherwise) is diet. If you eat more calories than you use, you will gain wait. If you eat less than you use – and you do this consistently – you will lose weight. Unfortunately for those looking to lose weight, our bodies are fairly resistant to weight fluctuation in general, but especially with weight loss.  If we eat an excess number of calories one day or a deficit of calories another, our bodies will increase or decrease our metabolism, respectively, in an attempt to maintain a static, unchanging body weight. This has nothing to do with what weight is a “healthy” weight – it’s simply because any change in the body is stressful, so it tries to avoid that stress, however possible.  Of course, all that being said, weight loss is still possible.

So, how much should you decrease your caloric intake?  We recommend consuming between 1100-1300 kcal for women and 1200-1400 kcal for men wanting to lose weight (yes, fat implied). Why this range? Well, like all things in life, there’s no cookie cutter recipe. However, we can get a good estimate by looking at current research and norms. The standard 2000 kcal ‘diet’ is the FDA-recommended intake for weight maintenance. We only point this out because the term ‘diet’ can be misleading and make people believe that eating this much is going to help them lose weight. It’s not. Research studies looking at weight loss often put people on diets with calorie intakes between 800-1200 Calories (spelled with a capital C, ‘Calorie’ is the same as ‘kcal’). This is on the rather extreme side, however, not by much. We recommend a less extreme calorie restriction (higher intake range) diet than these studies because more aggressive rates of weight loss have been shown to parallel with larger quantities of muscle loss, sometimes without any improvement in fat loss between two rates of weight loss [1]. A range is given because every person’s body reacts differently. Men typically have naturally higher metabolisms and, therefore, caloric needs. Additionally, one’s activity level can heavily influence their needs.

2)  The Importance of “Re-Feed” Days

We recommend implementing your diet in 2 week cycles, wherein one consumes their recommended range of Calories (stated above) for 11 days, followed by 3 days of ~2000 Calorie-diet consumption. Why should you alternate 11-day periods of calorie restriction with 3-day periods of maintenance consumption? It has to do with tricking your body in order to prevent it from compensating for the decreased calorie and avoiding weight loss. Some studies have investigated this method of intermittent dieting and found that, compared to continuous dieting, people’s resting metabolism decreases significantly less, resulting in more weight loss and – equally important – less weight regained following long periods of dieting once return to “normal” eating habits occurs [2].   Regaining weight following weight loss is extremely common, and recognized as perhaps the most frustrating aspect for repeated dieters.

3) Protein: Protect Muscle to Battle Fat

We recommend calorie consumption to be composed of 20%, 25% and 55% calories from fat, protein and carbohydrates, respectively. See chart below for recommended intake of each in grams, for various net caloric intakes. This recommendation for macronutrient breakdown is based on several factors. First and foremost, this diet attempts to make protein intake a priority. Muscle turnover is a naturally occurring process in all animals, humans included. We are constantly breaking down muscles, and almost simultaneously repairing/rebuilding them as needed. We use some of the breakdown products for energy, although the amount is very small at rest. However, when calorie intake is restricted for extended periods of time or by extreme quantities, this process is increased. Therefore, individuals are at increased risk for muscle loss while dieting, and as a result are recommended to increase protein consumption, which has been shown to replenish this breakdown and minimize the muscle loss [3]. Muscle mass (AKA Fat-free mass; FFM) is extremely important when it comes to weight loss because FFM has a large metabolic demand, and thus supports weight (and fat) loss even at rest [4,5].

4) What about Cardio?

Exercise – both aerobic and resistance training – is a critically important part of making any diet-induced general weight (fat and muscle) loss towards predominately fat loss, sparing FFM (muscle).  Both forms of exercise are known to be beneficial for ‘boosting’ metabolism for periods of time following activity. The center for disease control (CDC) recommends at least 150 minutes (2.5 hours) of moderate-intensity aerobic exercise and at least 2 days of resistance training for all major muscle groups every week. The CDC also lists 75 minutes of vigorous-intensity aerobic activity (with 2 days of resistance training) per week as an alternative option to the above stated recommendation [6].

Aerobic training is well known have beneficial effects on overall health, especially when investigating cardiovascular health. In addition, aerobic training is considered an effective tool in helping improve metabolic profiles, such as blood sugar levels and blood pressure, amongst others [7]. This is important for all individuals, but particularly those who are overweight or obese because there is additional stress being put on all bodily systems. In agreement with the CDC, we recommend at least 150 minutes per week of moderate intensity exercise. Moderate intensity aerobic exercise is typically considered to be things such as biking/cycling, rowing, walking or running, performed at between 50-70% of a person’s maximal heart rate (HR). You can estimate your age-predicted max HR (APMHR) using the equation APMHR = 220 – Age (years). Performing more than this amount, however, is highly recommended, if possible. Studies have shown that this amount of exercise is sufficiently effective for weight loss only when combined with diet (calorie) restriction. On its own, 150 min/week of moderate intensity aerobic activity is only sufficient to prevent further weight gain [8]. This 150-minute recommendation can be performed in several bouts of exercise throughout the week, as long as each bout is longer than 10 minutes. For example, you could perform just 10 minutes in the morning, midday and night and, if you performed did this each day you would exceed the minimum recommendation, having completed 30 minutes each day, with a grand total of 210 minutes by the week’s end. Higher intensities of aerobic training can be beneficial as well. However, several studies have compared the two intensities amongst real life populations and found that, particularly in overweight populations, higher intensity exercise is correlated with higher dropout rates (as in, more people give up on their programs – likely due to the very understandable fact that higher intensity is, well, harder) [9]. Therefore, we do not recommend this, because consistency is more important in the long run.

From a health profession standpoint, we do not recommend running as the mode of exercise when looking to use exercise to lose weight. This is based on the fact that running can place lots of stress on the joints. With excess weight and/or an inadequate “ramp-up” training period, this form of exercise can lead to higher chances of joint damage. Scientifically, this is because the force of body weight is multiplied (in the form of 'impact’) as you consider lower and lower joints of the body (i.e. impact hip<knee<ankle). Running should only be used as a mode of exercise once excess weight is shed, and appropriate training has allowed for months to years of physiological adaptation wherein the body can then handle that kind of stress.

5)  Muscle Gain = Fat Loss?

Resistance training is extremely important for weight loss. Resistance training can maintain or even increase FFM (muscle mass) during periods of calorie-restricted diets –something that aerobic exercise cannot do (diet + aerobic training alone will actually still lead to loss of muscle) [10,11]! Performing resistance training while dieting has been shown to be effective at preventing the dramatic decrease in resting metabolism that typically occurs with diets of calorie restriction, which in comparison, only occurs for 1-2 days following bouts of aerobic exercise. This has been deduced to be due to the greater amount of FFM [4].  Izumiya et al. showed this and more in a well-designed study investigating the effect of muscle mass and hypertrophy (growth) in mice models. The results were staggering.  Mice who had induced-muscle growth had higher metabolisms and preferentially burned fat over carbohydrates at rest, despite voluntarily consuming the same amount of food and being 40% less active than their control counterparts. In other words, mice with more muscle growth burned more calories – of which a higher percent was fat utilization (leading to less total fat) – despite doing less exercise and eating the same amount. In addition, these mice had healthier blood markers (e.g., improved blood sugar levels, improved insulin sensitivity, etc.) and less central fat distribution than the mice controls, which are things otherwise considered indicators of serious health risks [5]. Human medicine would interpret this to mean that the mice with more muscle growth were at lower risk of insulin resistance and/or diabetes, stroke, heart attack, and any number of related disease processes (e.g., kidney failure, fatty liver, peripheral vascular disease, etc.).

The Vital Take-Away

Seeing the number on the scale drop does not mean you lost fat, as these things can be very different. Losing weight begins with controlling how many calories you are taking in – and being smart about it. Cut calories, but not so dramatically or for so long (weeks on end) that your body can adjust by reducing its resting metabolic rate. You should have a few consecutive days without serious calorie restriction every 2 weeks, more or less. Keep the amount of protein you eat consistently high to prevent muscle loss and maximize fat burning. Aerobic exercise such as walking programs, cycling/spinning, or stairs can help boost your rate of fat loss. Resistance training can do this too, and additionally can decrease the chances of re-gaining weight after losing it.

Losing weight can be hard, but working towards it regularly and intelligently can mean success. There are no substitutes or shortcuts for dieting and hard work. No juice ‘cleanses’, fad diets or ‘fat-loss supplements’ can beat it (nor is there real proof that any of these work). So go out and get started. Step by step, day by day.