For people new to Ayurveda, the easiest approach is using the 10 pairs of Qualities (gunas) to adjust food & lifestyle factors. You can quickly determine which qualities are most present at the moment for you, and which might be exacerbating your health issue.
Remember, each of these pairs creates a continuum. No substance is exclusively heavy, or exclusively light. Instead, each substance sits somewhere along the continuum. Where it falls is defined in relationship to other substances.
The first pair of qualities is heavy-light (guru-laghu). Heavy means something weighs more, but it also can be taken to mean heavy to digest. Foods that sit closer to the heavy end of the spectrum include wheat, meat, cheese, dairy & root vegetables. Within this group, you can discover for yourself which foods are heavier to digest than others. Lifestyle habits that increase the heavy quality include excess sleep, waking late, being sedentary.
The light quality is also on the weight continuum. Automatically a beginner can judge that puffed grains like rice cakes or popcorn contain a light quality and sit on the far end of the spectrum from heavy foods. In addition, many fruits & vegetables are light to digest. Fruits like berries are lighter than melons. Lifestyle habits that increase the light quality include exercise, grazing style of eating, stress & excessive thinking.
Some examples of health problems caused by too much light quality can include osteoporosis, burnout, dizziness, rapid metabolism or heartbeat, sleep problems, anxiety & stress. Heavy quality contributes to indigestion, low energy, depression, weight gain and the range of metabolic disorders related to that.
Easy, right? The trick is to start to identify whether your health problems, and especially your digestion, come from too much heavy or too much light quality, and change your food & lifestyle habits to counterbalance, rather than exacerbate the problem.