I am a proponent of strength training over cardio because I feel it provides benefits beyond what cardio can achieve, like increased BMR, increased bone density, increased insulin sensitivity (that protects against type II diabetes) and increased joint strength (this will be a boon as we age). Don’t get me wrong but cardio has its benefits and people that are avid cardio doers should continue to do so, because at the end of the day what you like doing is the only thing that will work for you. No point fixing something that’s not broken!
Coming back to strength training, the one issue that confuses most people that take it up for fat loss is that the weighing scale doesn’t show a weight loss especially in the first few weeks. In fact people most often report a weight gain! Most people think of fat loss and weight loss as synonyms and this is the where the confusion happens. The truth is strength training builds muscle and muscle being denser than fat makes the weight go up even if you are losing fat at the same rate. And someone that’s taken strength training after a long time or for the first time will rapidly build muscle in the first 4-6 weeks while simultaneously losing fat. Hence the weighing scale will show an increased weight, at least in those initial 4-6 weeks. Once the muscle gain plateaus, you will still continue to see fat loss due to your higher BMR from the additional muscle you have gained. At that point the weighing scale will start registering the weight loss.
This is why I advise people to use waist size as a metric for fat loss. If you are a size 36 and now fit in a size 34 pant then you have lost fat no matter how much weight gain the scale shows. You see the waist is a good place to measure fat loss because most of the fat in the body is gained around the waist and it has the least amount of muscle (lower abdominal wall, cross-over between obliques/quadriceps and spinal erectors/glutes). So from a fat loss measurement standpoint is has the most signal-to-noise ratio (engineers must be smiling ear-to-ear now), meaning it will have the maximum fat loss (signal) with minimum muscle gain (noise). Any other place like shoulders or thighs will have more muscle gain (noise) than fat loss (signal) so you cannot accurately determine if you have lost any fat since the size increase is most likely from muscle gain. If you want to get even more accurate at measuring fat loss then use a calipers. You can buy one at amazon for $5-10 and here is a simple description of how to use it to measure body-fat level.
A weighing scale is a poor indicator of fat loss for people that actively strength train and remember when it comes to good health it’s fat loss that matters, not weight loss!