Tyler Robbins Fitness

B.Sc. Biochemistry, Certified Strength and Conditioning Specialist (CSCS), Certified CrossFit Trainer (CCFT/CF-L3), USA Weightlifting Level 1

Filtering by Tag: adipose tissue

Diet vs. Exercise for Weight Loss

A simple search of my blog will show you how many times I have written about this topic, but a new study published last month gives us even more insight - and confirmation, into what I have been writing about in the past.

A systematic review and meta-analysis on the effects of exercise training versus hypocaloric diet: distinct effects on body weight and visceral adipose tissue.Abstract

Exercise training ('exercise') and hypocaloric diet ('diet') are frequently prescribed for weight loss in obesity. Whilst body weight changes are commonly used to evaluate lifestyle interventions, visceral adiposity (VAT) is a more relevant and stronger predictor for morbidity and mortality. A meta-analysis was performed to assess the effects of exercise or diet on VAT (quantified by radiographic imaging). Relevant databases were searched through May 2014. One hundred seventeen studies (n = 4,815) were included. We found that both exercise and diet cause VAT loss (P < 0.0001). When comparing diet versus training, diet caused a larger weight loss (P = 0.04). In contrast, a trend was observed towards a larger VAT decrease in exercise (P = 0.08). Changes in weight and VAT showed a strong correlation after diet (R2  = 0.737, P < 0.001), and a modest correlation after exercise (R2  = 0.451, P < 0.001). In the absence of weight loss, exercise is related to 6.1% decrease in VAT, whilst diet showed virtually no change (1.1%). In conclusion, both exercise and diet reduce VAT. Despite a larger effect of diet on total body weight loss, exercise tends to have superior effects in reducing VAT. Finally, total body weight loss does not necessarily reflect changes in VAT and may represent a poor marker when evaluating benefits of lifestyle-interventions.

To summarize:

Calorie restriction (hypocaloric diet) is effective for weight loss. Exercise is effective for weight loss, although not as good as a hypocaloric diet. Hypocaloric diet and exercise in combination is effective for weight loss. Exercise is best at reducing visceral fat (adipose tissue packed in and around our organs).

So what is better for overall health?

Well, both calorie restriction and exercise are effective for improving your health in various ways, and the political answer would be that they are both effective in maintaining overall health, however what most people don't realize is that both have their strengths and weaknesses, pros and cons depending on your goals. Let me explain further.

Diet

  • For the most part, eat more than you burn to gain weight and eat less than you burn to lose weight.
  • Sure, it is possible that genetics can play a role in your metabolism and how you manage various macros (carbs, for example), but if you are gaining weight, then you are eating too much.
  • On the flip side, if you are losing weight, you are not eating enough.
  • Weight loss includes muscle loss, so by restricting calories and not resistance training you are potentially setting yourself up for strength and connective tissue loss.
  • As the above study tells us, dieting to lose weight is not as effective at removing visceral fat as exercise is. I have written about this before - "Skinny Fat" is Dangerous.
  • Losing weight too quickly (extreme calorie restriction) can cause a rebound effect known as the "Set Point Theory."
  • Protein consumption is extremely useful to maintain a healthy body weight. Make sure to increase your overall consumption as you age.

Exercise

  • Most people vastly over-estimate the number of calories exercise burns. This is especially true for individuals who just "show up" to the gym and don't exercise hard enough.
  • Yes, exercise can be helpful in healthy weight management, but it is not some magical formula that can prevent obesity if you do not diet appropriately.
  • Exercise is extremely beneficial for your brain, mood, bones, connective tissues, muscles, etc. Honestly, the list is so extensive, in my opinion, nobody should go without exercise, or more specifically, a well-rounded program consisting of cardiovascular exercise and resistance training.
  • As the study above tells us, exercise is more effective then dieting alone when it comes to reducing visceral fat - fat that can raise the risk of other diseases.
  • When it comes to changing the way you look, exercise is best at it can help increase lean mass (muscle), improve the appearance of your skin/hair, improve circulation, etc.




How to lose weight effectively

In order to lose weight, you must eat at a caloric deficit (consume less calories than you burn). In other words, over a period of time, say, 3 months to reach a weight goal, most days should be focused on eating less calories than your body burns for energy. This puts you at a negative energy balance.

A negative energy balance promotes the catabolism of your own tissues. In other words, your body begins to break down its own tissues to be used for energy. Sounds great right? Well, what most people don't realize is that although you are losing adipose tissue (body fat) during times of catabolism, you will lose some muscle mass as well (fat-free mass).

A study in Advances in Nutrition looked at how catabolism works and how our dietary choices affect what tissues are being catabolized:

Skeletal Muscle Responses to Negative Energy Balance: Effects of Dietary Protein
Sustained periods of negative energy balance decrease body mass due to losses of both fat and skeletal muscle mass. Decreases in skeletal muscle mass are associated with a myriad of negative consequences, including suppressed basal metabolic rate, decreased protein turnover, decreased physical performance, and increased risk of injury. Decreases in skeletal muscle mass in response to negative energy balance are due to imbalanced rates of muscle protein synthesis and degradation. However, the underlying physiological mechanisms contributing to the loss of skeletal muscle during energy deprivation are not well described. Recent studies have demonstrated that consuming dietary protein at levels above the current recommended dietary allowance (0.8 g·kg−1·d−1) may attenuate the loss of skeletal muscle mass by affecting the intracellular regulation of muscle anabolism and proteolysis. However, the specific mechanism by which increased dietary protein spares skeletal muscle through enhanced molecular control of muscle protein metabolism has not been elucidated. This article reviews the available literature related to the effects of negative energy balance on skeletal muscle mass, highlighting investigations that assessed the influence of varying levels of dietary protein on skeletal muscle protein metabolism. Further, the molecular mechanisms that may contribute to the regulation of skeletal muscle mass in response to negative energy balance and alterations in dietary protein level are described.

To summarize:

Sustained periods of negative energy balance decrease body mass due to losses of both fat and skeletal muscle mass

Mentioned above. If you eat less than you burn, your body will begin to look inward for energy. This is not a perfect system. Ideally, your body would burn only adipose tissue and leave your muscles alone, but sadly, that is not the case.

In general, the proportion of body mass loss at the recommended dietary allowance of protein (0.8 g·kg−1·d−1) is: ~75% adipose tissue and ~25% fat-free mass

So, if you were to consume protein at a "standard" dietary recommendation of 0.8g/kgxday (so that would be 65g protein for a 180lb person), then you will lose approximately 75% adipose to 25% muscle. In other words, every 10lbs you lose, 7.5lbs of that would be body fat and 2.5lbs would be muscle.

Consuming a high-protein diet may contribute to the regulation of muscle mass by maintaining whole-body protein turnover in response to either acute or prolonged periods of negative energy balance

Researchers have determined that consuming a diet higher in protein than the recommended 0.8g/kgxday can actually help to tip those numbers towards preserving even more muscle mass when at an overall caloric deficit.

A high protein diet during most studies was 1.5 g·kg−1·d−1, nearly twice the recommended dietary allowance of 0.8 g·kg−1·d−1

We're still not talking about crazy-high amounts of protein here, that is still only 123g of protein for a 180lb person.

Leucine-containing food products during exercise stimulate the mTORC1 pathway, increasing muscle protein synthesis and decreased whole-body proteolysis

So, foods containing the branch chain amino acid (BCAA) leucine have shown positive effects of further maintaining muscle mass, so make sure if you are eating at a caloric deficit, to make sure every one of those calories that you do ingest count, by loading up on leucine sources.

Recommended leucine intake is currently 14 mg·kg−1·d−1, but the amount required to maximize the stimulation of muscle anabolic intracellular signaling may be at least 40–65 mg·kg−1·d−1, and even up to 7–12 g·d−1 to contribute to the preservation of muscle mass during stressors such as energy restriction

Summary

You can use dietary means to try and reverse some of the effects of muscle breakdown during weight loss. I would also recommend adding resistance training to target all areas of the body to "signal" the body, letting it know that your muscles are being used and are needed. This will also help not only preserve muscle, but to preserve strength as well, as your goal of losing weight is pursued.