How Diet and Exercise Impact Visible Abs: Key Factors for Core Definition

Factors Affecting Abdominal Definition

Who doesn’t want a sleek, muscular core? Six-pack abs look really cool, and the abs/stomach generally rates a fairly high rank when men and (more often) women are asked to rate attractive body parts.

Obtaining visible abdominal muscles is based on maintaining a low enough body fat percentage. How low? Somewhere in the neighborhood of 6-12% for men and 14-20% for women. There is individual variation in how well your abs show, as some men will show prominent abs at 15% body fat while others will need to get down to 10% to see a six-pack. Also, there is always a bit of error in the measurement of the percent of body fat. If you are measured at 15% body fat, it really means you are somewhere between 11-12 and 17-18%.

The Importance of Nutrition for Core Definition

A healthy diet is the number one tool for optimizing body composition through increased muscle mass and reduced body fat. Any diet in which you consume fewer calories than you expend in a day will help you lose body fat. The trick is to find a sustainable approach that works for you. For most people, higher dietary protein, fiber, and physical activity are associated with better body composition. Protein intake, specifically, in the range of 1-1.6 g/kg/day, can improve body composition when coupled with either a reducing diet or a muscle-building exercise plan, which brings us to the role of exercise.

The Role of Exercise in Developing Abs

Let’s start by discussing what exercise generally can’t do: abdominal exercises typically will not melt the fat away from your abs nor make them more visible. The idea that exercise can reduce the body fat around the muscle you are training is termed spot reduction. The concept of spot reduction is mostly debunked. I say mostly, as one recent study found spot reduction possible after a 10-week intervention. The intervention consisted of abdominal training with high-repetition, aerobic-based intervals for four rounds x four min each with three-minute rest intervals between for three abdominal exercises -totaling 75 minutes/day four days per week of exercise devoted solely to abdominal training. Who has time for that?

Overall, exercise, while exercise alone (without modifying the diet) is not typically effective in reducing body fat, it is strongly linked to the prevention of weight gain. The best strategy for overall health is to combine aerobic endurance training with strength training, totaling about 150 minutes of exercise per week. Aerobic training can be done with any mode of exercise you enjoy. For strength training, I would focus more on ground-based large muscle mass, multi-joint exercises such as squats, deadlifts, and power cleans to strengthen the entire body. Research shows these exercises strongly activate the abdominal muscles. Further, large muscle mass multi-joint exercises increase overall strength and expend more energy than exercises that isolate the abdominal muscles.   

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