Does the following story sound vaguely familiar to any of you? You wake up and look in the mirror. You are delighted to find that your physique is looking very good. Your see that your body is leaning out nicely and your muscles are shaping up well. You put your workout attire on and pleasantly discover that the clothes are fitting you very well – snug in all the right places and loose where it matters. You hit the gym and kick some serious butt, setting strength records in multiple exercises. A couple of gym members pay you compliments, informing you that you are looking fantastic. Everything is going great, and your day is off to an excellent start. Then, you step on the scale, and all of your glee comes to a screeching halt. You’ve gained a few pounds, and knowing this absolutely ruins your day.

Over the past week, exactly three of my female clients have shared similar anecdotes. Upon telling them how great they looked or how well they’re doing, they mentioned that although they’re happy with their strength gains and physique improvements, they’ve packed on a few pounds since they started training and are therefore disappointed and discouraged.

Some people don’t care so much about what the scale says – they’re more influenced by other parameters such as how they look in the mirror or what their latest DEXA scan shows for bodyfat percentage. However, others are laser-focused on scale weight. Anecdotally, this scenario applies to a higher percentage of women than men, but some men will certainly be able to relate. It seems that many individuals have a target weight that they’re aspiring to reach, and they just cannot be content knowing that the scale isn’t congruent with this ideal notion (or moving toward this ideal notion), regardless of whether other forms of feedback appear to be promising.

Perhaps this number represents the body weight that the individual was at when they felt they looked their all time best (for example, in high school). Or maybe the number represents the body weight of their favorite celebrity, model, or athlete. Nevertheless, please allow me to tell you why you might indeed gain bodyweight following resistance training, but this is not necessarily a bad thing.

It’s All About the Diet

Before I go further, I want to point out the obvious. When you start lifting weights, you can either lose weight, maintain weight, or gain weight. How your body responds to strength training is largely influenced by your diet. If you’re eating like a bird, you’ll lose weight, and if you’re eating like a horse, you’ll gain weight. However, lifting weights will cause you to retain more muscle while you lose weight on a caloric deficit, and it will cause you to build more muscle while you gain weight on a caloric surplus. If you want to lose weight but find yourself gaining weight, then you’re eating too much. If you want to gain weight but find yourself losing weight, then you’re not eating enough. Got it? Good! Let’s move on.

Intracellular Water Gain: Pumping Up the Muscles

What if I told you that I possessed a syringe filled with special fluid that when injected into the muscles, would immediately improve their shape? This special fluid would have no negative side effects and is legal. Would you consider using it? Luckily, that’s not necessary. There is indeed a special fluid that does precisely this, and its name is water. But instead of injecting water into the muscles, all you have to do is lift weights. This causes intracellular water gain.

I can already envision my female readers seeing the term “water gain” and associating it with bloating, such as that experienced during pre-menstruation. However, the location of water storage largely determines whether the water retention positively or negatively impacts the physique – not all water retention is equal. There is no doubt that bloating, characterized by increases in extracellular water storage, negatively alters appearance. However, the opposite is true with regards to intracellular water storage.

Perhaps you’ve heard of bodybuilders describing how their muscles were flat. Much of what they do during the peaking phase prior to competition is designed to make the muscles appear full and the rest of the body appear dry. This is achieved by directing some of the body’s water content out of the interstitial space and into the muscle cells, which greatly enhances appearance. But this doesn’t just apply to bodybuilders. Think about the look of your favorite athletes – their muscles are probably full and shapely. As it turns out, this enhanced shape isn’t just attributable to increased muscle proteins; increased water also influences the size and shape of your muscles.

Here’s how it works. Your body contains a lot of water. Males possess a range of 38.5 – 73.5% water content, with an average water content of 58.3%, whereas females possess a range of 27.4 – 70.9% water content, with an average water content of 48.5% (1). So in general, humans are around 50% water.

Immediately following a strength training workout, your muscles will acutely retain water. In fact, 4 and 52 hours following a workout, your muscles will store 7 and 8% more water, respectively, and this increased water storage is associated with a 13 and 16% increase in cross sectional area, respectively (2). This jives with longitudinal research which shows that total body training performed 3 times per week for 16 weeks leads to 7.5% and 7.6% increases in total body water content for men and women, respectively (3). Furthermore, athletes that regularly perform resistance training tend to have lower densities of fat-free mass due to the increased water storage in their muscles (4-5). What’s fascinating is that extracellular water content doesn’t increase, only intracellular water content does, by 8.2% for men and 11.0% for women, respectively. The concurrent increases in skeletal muscle mass were 4.2 and 3.9% in men and women, respectively.

How is this so? The increased water storage is highly related to increased muscle glycogen. Following 5 months of heavy resistance training, muscle glycogen increases by 66% (6). It is thought that every gram of glycogen stored in the muscles will bring along 2.7 grams of water along with it (7), with other estimates as high as 3-4 grams (8). Interestingly, after just 3 days on a very low carbohydrate diet, glycogen stores in the body can decrease to 1/3rd of their initial values, and following this up with a high carbohydrate diet will cause these same individuals’ glycogen levels to rise by a factor of 6, essentially doubling their initial values (9). These fluctuating glycogen levels create the illusion of rapid fat loss and regain, but it’s really mostly water level fluctuation. And though most estimates put total body glycogen levels at approximately 400 grams, some individuals possess over 1,000 grams of glycogen in their bodies (10). This information helps provide clarity as to why individuals subjected to ketogenic very low calorie diets tend to lose 9.5 lbs in just 4 days, with the top responder losing 16.3 lbs!

Strength Training Makes You Denser, Up to a Point

Let’s put this into perspective. Let’s say a 130 lb woman undergoes a 3-month resistance training regimen. During this time, her weight stays the same; she doesn’t lose any weight or gain any weight. But she looks markedly different in the mirror. How can this be?

If she trained properly, she would have likely gained a few pounds of muscle mass, she would be storing more water in her muscles due to the increased glycogen, she would have lost several pounds of fat, and other small changes will have taken place such as increased bone density. Powerlifters tend to have the highest bone densities ever recorded (11), but this would be a minor factor in this example. Maybe she lost 6 lbs of fat, gained 3 lbs of muscle, and is storing 3 lbs more water in her muscles. This will markedly influence aesthetics, despite zero change in body weight.

When you strength train, weight tends to be subtracted from “bad” areas and added to “good” areas, and this shift in body composition makes a huge positive difference in your physique. And since muscle is 18% more dense than fat (12-13), improving body composition will decrease your overall volume. Since density equals mass divided by volume, you can see that increasing density without increasing mass can only be achieved by decreasing volume. Check out this 6 year progression of Amber Rogers, you’ll note that after just over a year, her weight didn’t change drastically, but she got smaller in overall size due to body recompositioning.

What About Exercise and Hunger Hormones – Why Am I So Darn Hungry All the Time?

If you’ve ever dieted down while undergoing resistance training and cardio, then you know how difficult it is to keep losing weight. If you’ve lifted weights competitively (as a powerlifter, weightlifter, or strongman) for any number of years, then you know how hard it is to stay a certain weight and avoid going up a weight class. But what does the research say about this?

There’s a TON of intriguing research on body weight set point theory (14-24). The body seems to have a set range of weight or set range of body fat percentage that it wants to remain at, and the internal mechanism is located in the lateral hypothalamus, and the more weight or fat you lose, the harder it is to maintain that new weight or body fat percentage. 

With regards to appetite hormone effects of exercise, there really isn’t much to go by since the vast majority of the research is short term in nature (29). For example, 2 days of intensive resistance training has been shown to significantly decrease leptin and ghrelin levels (25). Twelve weeks of exercise showed that aerobics were more effective than strength training at satisfying hunger (26). Aerobic and resistance training suppress hunger for 1-2 hours after the training session (27), but this might be the case with men more so than women (28). Moderate and high intensity exercise appear to effect hunger hormones similarly (30). That’s about all we know; there is yet to be a high quality long term trial conducted on hunger hormones following resistance versus aerobic training.

Should We Even Weight Ourselves?

The answer to this question is yes, you should weigh yourself. Well, you should as long as it doesn’t make you crazy. Research overwhelmingly shows that daily self-weighing is good for weight loss, that breaks in self-weighing lead to increased risks of weight gain, and that self-weighing is not associated with depression or anxiety (31-32). However, the scale is just one indicator that on its own fails to capture the entire picture.

What Indicators Should We Pay Attention To?

You should rely on a variety of indicators of fitness progress, including:

• scale weight
• body fat levels
• measurements
• strength levels
• how clothes fit
• progress pictures
• compliments from others
• how fit and conditioned you feel
• other measures of health such as blood pressure, cholesterol profiles, triglycerides, blood sugar, insulin sensitivity, inflammation, etc.

One of the clients who was frustrated at her scale weight showed up to train with me a few days later with a huge smile on her face. She put on a pair of once snug work pants and found that there was an inch and a half gap in the waist area. She also took some progress pictures and could clearly see major improvements in her physique. Her husband, friends, and co-workers are complimenting her like crazy, her booty is rockin’, and her strength is sky-rocketing (in just 4 months of strength training, she’s deep squatting 155 lbs, deadlifting 225 lbs, benching 95 lbs, very close to getting her first chin-up, and hip thrusting 295 lbs for 4 reps).

Conclusion

Self-weighing is a good idea, as long as it doesn’t cause you to feel loco en la cabeza.  But if you only rely on the scale to inform you of your progress, you will be missing the forest for the trees (getting so caught up in the minutia that you fail to see the big picture). Everybody knows that resistance training does a body good and makes the body look better. Lifting weights will cause you to lean out, become denser, and lose overall volume. It will also cause your muscles to swell so they have the coveted 3D athletic look that so many desire. This muscular swelling is associated with some weight gain, so don’t sweat it if you gain a few pounds when you begin training. It’s caused by increased muscle glycogen storage and subsequent increased water storage.

References

1. Total body water volumes for adult males and females estimated from simple anthropometric measurements
2. Concomitant changes in cross-sectional area and water content in skeletal muscle after resistance exercise
3. Resistance training promotes increase in intracellular hydration in men and women
4. Muscularity and the density of the fat-free mass in athletes
5. Density of the fat-free mass and estimates of body composition in male weight trainers
6. Biochemical adaptation of human skeletal muscle to heavy resistance training and immobilization
7. Muscle glycogen storage and its relationship with water
8. Variation in Total Body Water with Muscle Glycogen Changes in Man
9. Diet, Muscle Glycogen and Physical Performance
10. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition
    
11. Case study: Bone mineral density of two elite senior female powerlifters
12. Adipose tissue density, estimated adipose lipid fraction and whole body adiposity in male cadavers
13. Density, fat, water and solids in freshly isolated tissues
14. Set points, settling points, and the control of body weight
15. Defense of differing body weight set points in diet-induced obese and resistant rats
16. Metabolic defense of the body weight set-point
17. Body weight set-points: determination and adjustment
18. Evidence that transient nicotine lowers the body weight set point
19. Dietary fat and body weight set point
20. Body weight setpoint, metabolic adaption and human starvation
21. Role of set-point theory in regulation of body weight
22. Is there evidence for a set point that regulates human body weight?
23. Set-point theory and obesity
24. Role of set-point theory in regulation of body weight
25. Effect of 2 days of intensive resistance training on appetite-related hormone and anabolic hormone responses
26. Beneficial effects of 12 weeks of aerobic compared with resistance exercise training on perceived appetite in previously sedentary overweight and obese men
27. Influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin, and peptide YY in healthy males
28. Comparable effects of moderate intensity exercise on changes in anorectic gut hormone levels and energy intake to high intensity exercise
29. Acute exercise and hormones related to appetite regulation: a meta-analysis
30. Exercise-Trained Men and Women: Role of Exercise and Diet on Appetite and Energy Intake
31. Are Breaks in Daily Self-Weighing Associated with Weight Gain?
32. Self-weighing in weight management: A systematic literature review