Protein Scientist Reveals New Study on High Protein Diets & Resistance Training for Fat Loss

Dr. Ormsby argues that resistance training is underutilized for fat loss because people associate it only with muscle gain and think cardio is the only way to burn fat. He cites multiple lines of evidence: their microdialysis studies showing increased glycerol (lipolysis) after resistance training in both lean and obese individuals; the bariatric surgery study where resistance training preserved muscle and shifted weight loss to almost entirely fat; and the emerging muscle-fat crosstalk mechanisms. He emphasizes that resistance training provides early 'wins' through strength gains, which can motivate people who are discouraged by slow scale weight changes. For those carrying excess weight, resistance training can be safer and more enjoyable than high-impact cardio, and it reshapes the body rather than just creating a smaller version of the same shape.

Dr. Ormsby describes a study where they recruited individuals scheduled for bariatric surgery. The standard pre-surgery diet was 800 kcal/day with very low protein (about 0.55 g/kg). Concerned this would cause excessive muscle loss, the research team convinced the medical staff to increase protein in both groups, bringing total calories to around 1,200. One group did resistance training, the other did basic calisthenics. After 12 weeks, both groups lost significant weight, but the resistance training group lost only 4% of that weight as muscle, compared to 25% in the calisthenics group. This demonstrated the power of combining protein and resistance training to spare muscle even under extreme calorie restriction. He stresses that when cutting calories, protein should remain high while other macronutrients are reduced.

Dr. Ormsby discusses two studies that specifically tested the timing of cardio after resistance training. One group waited 20 minutes, the other 120 minutes, before an aerobic session. Fat oxidation was higher in the 20-minute group. He explains that waiting 120 minutes is not only less effective but also impractical—most people would eat during that time, which would further reduce fat oxidation. The 20-minute window keeps you in a fasted, metabolically activated state, taking advantage of the 'double hit' on metabolism. This protocol is especially useful for those who want to combine both modalities in one gym visit.

Dr. Ormsby shares an anecdote from his early studies (around 1999-2000) where participants dropped out despite improvements in body composition (clothes fitting better, belts tighter) because their body weight didn't change. This taught him that people are heavily driven by the scale. To combat this, his team now builds in periodic strength testing. When participants see their strength numbers going up, it provides a tangible win and momentum to continue. This is especially important because resistance training may not cause immediate weight loss due to muscle gain offsetting fat loss, but strength improvements are rapid and motivating.

Dr. Ormsby references Bill Campbell's work on diet breaks, noting that weight loss is not linear and breaks can actually improve long-term success. In one of his own studies, they gave participants one full day off per week. For some, it was a helpful psychological reset without overeating. However, for others, it led to 'creep'—starting the break earlier or extending it, eventually turning one day into two and causing them to fall off track. He advocates for a sustainable approach where breaks are woven into the plan as part of the strategy, not as a reaction to deprivation. This prevents the feeling of making a mistake and keeps the overall trajectory positive.

Dr. Ormsby explains that for a long time, fat was thought to be almost inert, but now we know it's highly active and communicates with many tissues. However, it wasn't solidified that muscle and fat directly communicate to enhance lipolysis. In the last couple of years, studies have shown that muscle damage from resistance training releases myokines and cytokines like IL-6 and TNF-alpha, which stimulate lipolysis. More recently, a paper demonstrated that extracellular vesicles from muscle carry a molecule called miR-1. This miR-1 acts as a brake on lipolysis; when it reaches fat cells, it stops that brake, allowing lipolysis to accelerate. This ongoing communication means resistance training is directly influencing what happens in fat tissue. The research is still early, but it confirms that these tissues are talking, and resistance training is a direct fat-loss stimulus.

Dr. Ormsby notes that growth hormone's role in muscle growth has been 'sort of shut down' acutely. However, growth hormone is also lipolytic. In their microdialysis studies, they saw growth hormone rise significantly after resistance training in both lean and obese individuals. They hypothesized that this spike was stimulating the lipolytic response. To test this, another group perfused growth hormone directly into subcutaneous belly fat via a microdialysis probe and observed a much greater increase in glycerol, indicating heightened lipolysis. This suggests that the well-known growth hormone elevation from resistance training is actually a fat-loss signal, not a muscle-building one. This reframes how we interpret the hormonal response to training.

Dr. Ormsby's lab compared lean and obese sedentary individuals during resistance training using microdialysis to measure glycerol (a marker of lipolysis). Both groups increased lipolysis, but the obese group's response was significantly blunted. They explored why by looking at insulin and growth hormone. Insulin, a potent inhibitor of lipolysis, was higher in the obese group at every time point. Additionally, the growth hormone response was blunted—it rose, but not nearly as much as in the lean group. In earlier aerobic studies, giving phentolamine (an alpha-receptor blocker) normalized the lipolytic response in obese individuals, suggesting a larger alpha-adrenergic 'brake.' However, in their resistance training study, phentolamine only increased lipolysis in the lean group, not the obese, indicating that the alpha-receptors are involved but not the main player. The combination of high insulin and low growth hormone appears to create a double brake on fat mobilization in obesity. This means that once someone becomes obese, their body actively resists fat loss, making the initial phase of weight loss particularly challenging.

Dr. Ormsby explains that while the exact duration of the lipolytic window after resistance training isn't directly measured, older data on fat oxidation suggests it lasts 24-48 hours. Two specific papers compared doing an aerobic session either 20 minutes or 120 minutes after resistance training. The 20-minute interval resulted in better fat oxidation. He reasons that at 20 minutes, you're still 'revved up' from the first session, taking advantage of a double hit on metabolism and the muscle-to-fat signaling (like miR-1). Waiting 120 minutes is not only less effective but also impractical for most people, who would likely eat during that gap, further blunting the response. This suggests that for those aiming to maximize fat loss, a short transition from weights to cardio is ideal, and it should be done fasted or without feeding in between.